I appreciate your site as I am trying to make up a set of as many complete sets of drivers complete with individual handles permanently attached as a gift for my son. British Aerospace and Airbus are also users of this fastener. Heat-treated steel for dependable strength. These screws are often found in children's toys from fast food restaurants, as well as vacuum cleaners, fan heaters, elevators, camping stoves, golf clubs, Breville kettles and Master Locks, among others, Sizes include TA14, TA18, TA20, TA23 and TA27. [58], The Recex drive system claims it offers the combined non-slip convenience of a Robertson drive during production assembly and Phillips for after market serviceability. What a fantastic gift idea for your son. While they are distinguished under close inspection by the angle at the tip of each of the 12 points (with a 90 angle on the XZN, instead of 60) the general similarity and ability to insert the wrong tool can cause damage to the head. Wiha Square bits are designed for applications requiring high wear resistance. Thanks for the charts and mentioning colour coating. [50][54] Compared to the hexagon socket drive, spline socket drives are less likely to strip for the same amount of torque; however, the spline socket drive is not much more strip-resistant than a Torx drive. [70] These use special circular or oval cam-shaped heads that require complementary socket drivers. ROBERTSON SQUARE DRILL BIT SET - 10 Piece Set in the Following Sizes #0, #1, #2, #3, and #4 (2 of Each Size) CONVENIENT PLASTIC STORAGE CASE - Our . The tool recess is a perfect, sharp cross, allowing for higher applied torque, unlike the rounded, tapered Phillips head, which can cam out at high torque. When a Phillips is Not a Phillips Plus So Much More! PZ1 is normally used on screw diameters from 2-3mm, PZ2 from 3.5-5mm and PZ3 from 5.5mm to 8mm. [citation needed]. One-way screws are commonly used in commercial restroom fixtures and on vehicle registration plates, to prevent vandals from tampering with them. What other wood screw sizes will fit the opening of a Robertson Screw that would need a #1 screwdriver? They are still commonly used in machinery fastening. 4-bit computing refers to computer architectures in which integers and other data units are 4 bits wide. Company of Worcester, Massachusetts, was put into bankruptcy in 1987 and liquidated in 1990. Torq-set is a cruciform screw drive used in torque-sensitive applications. An advantage of external drive fasteners is that they lack a recess in the head, which can collect water, dirt, or paint, which can interfere with later insertion of a driver tool. Also known as an ECX or Combination Tip drive. Much like Phillips screwdrivers, Robertson drives use a numbering system. Just snap a photo and we'll find and store your user manuals, receipts, and product information in one easy-to-find place! A flat head screwdriver is also sometimes referred to as a slotted screwdriver. For the majority of people in the US, a good set of slotted and Phillips screwdrivers would be considered essential. Some drive systems will cam-out at lower torques, others at higher torques. aircraft. Oh for a world full of Robertson heads and the drivers of course. Less prone to slipping than slotted screwdrivers, the design still has some issues at high torque that have since been resolved in newer cruciform designs. A cross-head screw with a two-step driver design, with the blade diameter stepping up at a distance from the point. The TA is a type of screw drive that uses a triangle-shaped recess in the screw head. Below you will find the 5 most common screw head shapes with the various sizes available. These sockets are also known as Robertson bits. Triple-square drive fasteners have been used in high-torque applications, such as cylinder head bolts and drive train components. Pozidriv screws have a set of radial indentations (tick marks) set at 45 from the main cross recess on the head of the screw, which makes them visually distinct from Phillips screws.[10]. Two-Piece #2 x 2 in. It is used primarily in the automotive industry in high-torque applications, such as brakes and driveshafts. True tamper-proof - rather than merely resistant - screw drives include the breakaway head and one-way screw drives. THANK YOU for publishing this page as it is greatly appreciated. The snap ring notch on the bodies of insert bits helps them hold firmly in bit holders. [71], The Ultra-Lok, and Ultra-Lok II are some of these designs that use custom keyed drivers, which tend to be confined to industrial and institutional uses that are unavailable to the average layperson. A square screw drive uses four-sided fastener heads which can be turned with an adjustable wrench, open-end wrench, or 8- or 12-point[62] sockets. which bit size fit into the screw square? Either method leaves only a smooth bolt head exposed. Turn many sizes of square, hex, and 8-point fasteners with one socket. Also called BNAE NFL22-070 after its Bureau de normalisation de l'aronautique et de l'espace standard number. ", "When a Phillips Is Not a Phillips Plus So Much More! One example familiar to laypersons is for the attachment of wheels and spare tires of passenger vehicles to deter theft; one of the lug nuts on each wheel may require a specialized socket provided with the set of lug nuts. [27], Phillips II recesses are compatible with Phillips drivers, but have a vertical rib in between the cruciform recesses that interacts with horizontal ribs on a Phillips II driver to create a stick-fit, and to provide anti cam-out properties (the ribs are trademarked as "ACR" for Anti Cam-out Ribs). Youfu has been engaged in the production and sales of precision hand tools, electric tools, accessories, and household repair tool kits for more than 10 years. Copyright 2021.Kingsdun All rights reserved. That would be a machine screw. The TS designation is ambiguous as it is also used for a Torq-set screw drive. , NoCoRode, Undersized, Squarer Bit SKU: HCU-0210 $1.91 As low as $1.68 Add to Cart Two-Piece #2 x 3 in., NoCoRode, Undersized Square-Drive Driver Bit SKU: HCU-0310 $1.93 As low as $1.70 Add to Cart Two-Piece #2 x 4 in., NoCoRode, Undersized Square-Drive Driver Bit SKU: HCU-0410 $2.47 As low as $2.17 Add to Cart I created PDFs for socket and wrench sizes but found there to be little demand for those. Not as widely used as other drive systems. Phillips drives have become a very popular drive when it comes to precision work, thats why it is used in electronics and laptops. Fnnk@y/:GLp_"3G{ Now that the original patents and licensing restrictions have begun to expire, Robertson screws are gaining in popularity worldwide. This is potentially confusing if looking for the more unusual 12-spline flange type. Both the tool and the socket have a slight taper. They are commonly used to drill lathe centres and spotting drills, i.e.marking holes to guide twist drilling. So this left me puzzled as to which one to get, as I was not aware that Philips can be so different with each size. Triple-square fasteners are referred to as "spline" in the UK. Metric sizes of the hex are specified by ISO 4032 and ISO 4033, plus ISO 4035 for Jam Nuts, and ISO 4014 and ISO 4017 for hex cap screws, ISO 4018 for Hex head screws (grade c). The bottom of the recess is flat, and the point of the driver has to be blunt. It looks like Torx but has a knob in the centre of the screw. The Slotted/Phillips head is often used in attaching knobs to furniture drawer fronts and combined slotted/pozidriv heads are so ubiquitous in electrical switchgear to have earned the nickname "electrician's screws". This Maximum product carries a no time limit warranty against defects in workmanship and materials. Thanks!! There is a new screwdriver out now and Ive found it mostly in electronics. At a minimum, a screw drive is a set of shaped cavities and protrusions on the screw head that allows torque to be applied to it. %PDF-1.3 A combined slotted and Torx drive screw was used in electronics manufacturing. Pros: Square bit design offers high torques, low cam-out performance, are easily used one-handed, and are self-centering. Designs with more contact points to the fastener distribute pressure more evenly, have more driving power due to increased contact area, can handle more torque before camming-out, will cam-out less, and will wear more slowly by consequence. Pozidriv bits can operate at higher torque than Phillips systems before camming-out. The most common sizes in use for consumer electronics are DCT-20 and DTC-27. Phillips screwdrivers can be used on many different cruciform screws. [48][53] The spline socket is also preferred over the hexagon socket in screws that must be subjected to high driving torque and in applications requiring high reliability of the fastener. Part of this is the fact that a Phillips driver is sized through a number code instead of an Imperial/SAE measurement and can fit two to five sizes of head above its own. [34] Solid modeling is used for the design of the punches, bits, and screws. It can also sometimes be removed by attaching a precision drill chuck tightly to the screw head, in a manner similar to removing screws that have broken heads.[68]. You can identify the size required for a random screw by measuring the width of the slot and comparing it to a Torx sizing chart. Common in the 19th and early 20th centuries, when it was easier and cheaper to manufacture than most other drives, it is less common today (although still easy to find) because the external hex is now cost-competitive and allows better access for wrenching despite nearby obstructions. Several variations on the torx bit are available, such as tamper-proof designs that include a pin in the center of fasteners. Pros: High torque, low cam-out. The Mortorq drive, developed by the Phillips Screw Company, is a format used in automotive[32] and aerospace applications. The hexalobular socket screw drive, often referred to by the original proprietary brand name Torx ( /trks/) or by the alternative generic name star drive, uses a star-shaped recess in the fastener with six rounded points. To measure an unmarked key, for example, you would measure the distance between two opposing ends. While the largest called PMT-7 can be used on screws with a head diameter of 35mm. Standard 12-point hex socket bits and wrenches fit these screws. [20] One advantage over the Phillips drive is that one driver or bit fits all screw sizes. Tel. I'm impressed." Unicode character can be 2 or 4 bytes, so that would be 16 or 32 bits, whereas Windows-1252 sometimes incorrectly called ANSI is only 1 bytes so 8 bits. : 1-800-479-0056 Square bit sizes are designated by found numbers, expressed as S0, S1, S2, S3, etc. The most common bit sizes are covered: two Slotted (3/16in and 1/4in), two Phillips (PH1 and PH2) and two Nut Drivers (1/4in and 5/16in). We include all 9 known sizes of triple square bit (M4, M5, M6, M8, M10, M12, M14, M16 and M18) PLUS an extra long M10 for inner CV bolt access. All of these sizes can be searched by clicking the tab at the top of the page. This type is usually found in cheaply-made roofing bolts and the like, where a thread of 5mm (0.20in) or above has a large flattened pan head. It would be great if you could recommend which screwdrivers are useful for day-to-day home use. The design is similar to a square drive (Robertson), but can be engaged at more frequent angles by the driver bit. An External Torx version exists, where the screw head has the shape of a Torx screwdriver bit, and a Torx socket is used to drive it. Their several access positions and low cam-out make torx bits fast, efficient, and wear resistant. The double-square drive is two squares superimposed at 45 rotation, forming an 8-pointed star. [65] In addition to breakaway bolts, breakaway nuts of similar design are available.[66]. They are still commonly used in machinery fastening. Apple uses Y-type screws to secure the battery on the 2010 and 2011 MacBook Pro, as well as an extremely small type in the Apple Watch, iPhone 7 and iPhone X. The hex head is used to drive the bolt into the countersunk hole, then either a wrench or hammer is used to break the shank and hex head from the flat head, or it is driven until the driving head shears off. The main practical difference is in driving screws into vertical surfaces: that close to a near-vertical surface to drive the screws into the drivers, Supadriv has superior bite, making screwdriving more efficient, with less cam out. A Robertson screw, also known as a square screw [4] or Scrulox, [5] is a type of screw with a square -shaped socket in the screw head and a corresponding square protrusion on the tool. Some consumer appliances, such as espresso machines from Jura Elektroapparate, use a proprietary screw head with an eccentric oval to dissuade owners from servicing their own machines. A correctly sized JIS driver will engage at full depth into a Phillips or Pozidriv head screw slightly loosely, but without damage. Vintage Irwin Wooden Boxed Set of 13 Auger Hand Drill Solid Center Brace Bits. A reply would be appreciated. Instead, a one-way screw can be removed by drilling a hole through the head of the screw and inserting a screw extractor. [34] This allows the Mortorq drive to work in smaller and more complex builds. Thanks Gonzo. Rob. Bit Size #1 #2 #3 Max 0.091 0.1126 0.133 Min 0.09 0.111 0.1315 Bit and fastener sizes must match exactly. With the fewest points of contact of any system, slot bits cam-out at very low torque. How about an actual size photo of every size? Hi, my Name is Istvan, I live in Hungary. The Robertson drive is commonly referred to as a square drive and is very popular in both electrical and construction fields. [30], As of 2022, both Frearson screws and Frearson bits are readily available in several sizes. ]AGws2Z+JVGPZt ddW}}QFYK(|o-zq&c)Kk75GvTs8jtFaF&T#3dJF56;Qca4UsRTSEt7 (\!@T3MMvcTQC]1*|{XdN9j~p-BkT"]9]?\8 ko'DxIa&ro,-V>/FT(!Q! Although their tendency to cam-out increases wear to bits and fasteners, they cam-out much less easily than slot systems and reduce the risk of damaging the material being worked on as they prevent over-tightening. Would that be between opposing flat faces, or between points? Square bit sizes must match exactly to fastener sizes. stream c7m[w7a0VZwcHTPc+-nTUq[ ^im;Uw![7mw4T+mb44n:x(wN5Awd3hiJX? However, the security feature of this design can be bypassed by using some type of pliers if enough force is applied. This table shows end mill diameter sizes for inch, metric, and micro milling bits from 0.005" to 1". Please do one for Y-Screws (or Tri-Wing Screws), Ive literally been searching on & off for YEARS now-Thanks a lot Nintendo(!). Their shape makes slot fasteners easy to turn with common objects. Bureau de normalisation de l'aronautique et de l'espace, "When a Phillips is not a Phillips Plus So Much More! The square is 2,9*2,9mm. This form was the first type of screw drive to be developed, and for centuries, it was the simplest and cheapest to make. The Phillips screw design was developed as a direct solution to several problems with slotted screws: high cam out potential; need for precise alignment to avoid slippage and damage to driver, fastener, and adjacent surfaces; and difficulty of driving with powered tools. "JIS" standardized cruciform-blade screwdrivers are available for this type of screw, and should always be used to avoid head and driver damage. https://www.legacy.com/obituaries/rrstar/obituary.aspx?n=bernard-reiland&pid=107223629, The development of the Torx screw began in 1967, was patented in 1971 and was invented by Bernard F. Reiland for the then Camcar Textron company. Robertson, a Canadian. 1-48 of over 3,000 results for "square drill bit" RESULTS Price and other details may vary based on product size and colour. The design is similar to a square drive (Robertson), but can be engaged at more frequent angles by the driver bit. These screws can be driven with standard Robertson bits. Now, you know that: 1 Bit = Single Binary Digit (1 or 0) 1 Byte = 8 Bits. Finish Nailer Repair - Replacing the Driver Guide (Ridgid Part # 79004001022). I would need Robertson#1 screwdriver to screw it in with once I have repaired the wood. Files are sent over to manufacturers containing these models so that there is no miscommunication and all the parts are the same across the board. The Robertson drive is commonly referred to as a square drive and is very popular in both electrical and construction fields. TP3 (sometimes referred to as tri-lobe or tri-lobular) uses a Reuleaux triangle-shaped recess in the screw head, to make it semi-secure because it cannot be driven by a flat-blade screwdriver[84] and is not readily driven, as Tri-angle is, by hex keys. Like the Phillips screwdrivers, Robertson drives also make use of a numbering system. This screw drive is often referred to as an improved version of the Phillips drive. Torx Plus is an improved version of Torx that extends tool life even further and permits greater torque transfer compared to Torx. More commonly referred to as Allen wrenches, these screwdrivers sometimes come in an L-shaped shank with no handle, as multiple retractable sizes with a centrah handle (ala Swiss army knives), or even with a ball-shaped tip. Hex bits are sized by their diameter measurements in either the English standard or metric systems. A U-drive screw has a helical thread with an angle acute enough to be driven by a hammer or pressure from an arbor press, and thus has a domed head with no means of turning it. Superficially it looks like a Phillips screw with narrower and more vertical slots, to give less tendency to cam out. Square bit sizes are designated by found numbers, expressed as S0, S1, S2, S3, etc. This can also prevent attempts at turning the screw with a small flat-bladed screwdriver. drive is available in 5 different sizes. Sometimes referred to as the star drive due to its rounded 6-point star shape, the Torx drive is designed to function at higher torques and have a longer lifespan than other popular screwdriver types. Sounds like a #1 (green . Although old, their six sided shape gives them great usability and makes them inexpensive to manufacture. This driver has a tip measuring 5 mm. Increased cam-out with slot bits and fasteners increases their wear rate. To extend the life of power bits, it's best for shoppers to buy high quality bits made from wear-resistant materials. Pros: Although old, their six sided shape gives them great usability and makes them inexpensive to manufacture. A security Torx screw drive is a common modification to socket and cruciform style drives to make the fastener more tamper resistant by inserting a pin in the center of the female socket, requiring a tool with a corresponding hole to drive the fastener. In practice, drivers for the fasteners may be interchangeable, but should be examined carefully for proper fit before application of force. Flat-blade jeweler's screwdrivers and the tips found in .mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}14-inch or 6.4-millimeter drive sets are generally hollow-ground. (see Table 1). Actually a great idea. The most common of these are a combination of a slotted/Phillips head. Kobalt Screwdrivers 10-Piece Plastic Handle Assorted Screwdriver Set. Although they are often installed directly into jaw chucks by users, insert bits were originally designed to fit in the ends of extension adapters. Having different socket wrench sizes will allow you to operate different socket sizes based on your particular needs. What size Tri-point or Y driver is comparable to T7 Torx? ACR Phillips II Plus is a screw-drive design that can be driven by a #2 Phillips driver or a #2 Robertson driver, but when driven by a Phillips II Plus Bit, the combination results in a stick-fit interface. Because of this, a regular Phillips or flat-blade screwdriver will not fit the head. They are sometimes also cut for Phillips head or slotted screwdrivers, as well as having the knurling for finger grip. Torx drives have different numbers based on the different distances between two opposing points. The Phillips drive system improves upon the slot system in many ways. These hex keys are sometimes referred to as Allen wrenches and these screwdrivers usually come in an L-shaped key with no handle. Robertson screwdrivers are easy to use one-handed, because the tapered socket tends to retain the screw, even if it is shaken. This makes it easy to determine the key needed for a specific hex screw when youre not sure of the size. Some of these could be easily hard laminated for DIYer workshop reference material. Several variations on the torx bit are available, such as tamper-proof designs that include a pin in the center of fasteners. They are also known as Gamebit screws, due to their use on some video game consoles. 3/4" Square Drive Size Quickly position these sockets on square and external 8-point fasteners. The design was adopted by some parts of the aerospace industry, led by Lockheed in the early 1970s on the L-1011, but met with mixed results due to complaints of insert damage during installation. It consists of 12 equally spaced protrusions, each with a 60 angle. Radio Material School, Naval Research Laboratory. Because power bits are generally more expensive than insert bits, they're usually bought to last longer than insert bits. You'll reach for this handy tool again and again. Owing to its six-fold symmetry, a Torx driver can also be used as an improvised substitute for a hex driver, although careful sizing is critical to prevent stripping the socket. In non-security applications, a breakaway head fastener is sometimes used as a crude torque limiter, intended to break off at an approximate torque limit. Hex drive systems are very old, and their bits are commonly called "Allen" wrenches or keys. Like the Phillips screwdrivers, Robertson drives also make use of a numbering system. With such a different approach to driving system design, square bits offer unique advantages and are increasingly appreciated by tool users. The above link provides a printable and downloadable chart of the table below. Also, some external drives can be engaged from the side, without requiring large inline clearance for tool access, which allows their use in tight spaces such as engines or complex pipework. Type A, also known as a "standard clutch", resembles a bow tie, with a small circular "knot" at the center. A good drill size chart can also be used as a handy decimal equivalence chart as well as to convert decimal sizes to metric. Breakaway fasteners used in a non-security application may have a second driveable surface (such as a hex head) to allow later removal or adjustment of the fastener after the initial breakaway installation. They are commonly found on German vehicles such as BMW, Opel, Mercedes, and those from the Volkswagen Group (Porsche, Audi, Seat, Skoda, and Volkswagen).[38]. Technically its for a 2.82mm 2.86mm square recess but that sounds like what you have. Updated the article to include Pozidriv sizes. Moreover, it cannot be turned by typical consumer- and professional-grade socket drivers, which possess either six or twelve points (neither of which are multiples of five). A hex screw drive uses six-sided fastener heads, and the fastener is known as a hex head cap screw. This reduction of weight within the head height was able to create lighter assemblies for many aerospace projects. -Clever Jeff . They are difficult to remove with conventional tools because the slot is designed to cause cam out when even minimal torque is applied in the direction to unscrew it. 4. [citation needed], Line Head and Line Recess screw drives are Japanese systems with male, female and tamper-resistant configurations. Have you ever looked at a screwdriver set and thought There are more sizes than Ill ever need only to read reviews and find out theyre incomplete? Lot of 21 Vintage Hand Drill and Auger / Bits Stilletto,perfect,swan,irwin. Youfu Tools Launches Limited-Time Wholesale Promotion on Electric Screwdrivers! Smaller versions are now used on the iPhone 4 and subsequent models, the MacBook Air (since the late 2010 model), the MacBook Pro with Retina Display and the 2015 MacBook. In 2006 Textron Fastening Systems was sold to Platinum Equities, LLC, of Beverly Hills, California. The Phillips company improved upon their Phillips drive system by developing Pozidriv bits and fasteners. 1 Megabyte or 1 MB = 1024 Kilobytes (KB) 1 Gigabyte or 1 GB = 1024 Megabyte (MB) 1 Terabyte or 1 TB = 1024 Gigabytes (GB) The next time you wish to convert from one unit to another, just remember these data converter basics. [16] However, a 1949 refinement to the original design described in US Patent #2,474,994[17][18][19] describes this feature. Torx bits are sized with round numbers (often increments of 5), and expressed T10, T15, T20, etc. (for Different Surfaces), 9 Best Car Buffers and Polishers (Safe and Easy Detailing), https://www.hausoftools.com/blogs/news/history-and-origin-of-torx. For example, seems to me that phillips #0, #1 and #2 will be enough for more than half of the screws Ill encounter around the house. Save my name, email, and website in this browser for the next time I comment. In Asian version of Windows and some others . One bit is either on/off, yes/no, or 0/1. Shape allow high torque fastening without cam-out. An alternative design leaves a low-profile button head visible after installation. I concur!!! These screwdrivers are the easiest to recognize because of its wedge-shaped end. They are found on IBM computers, as well as Nintendo and Sega systems and their game cartridges. The Pozidriv, sometimes incorrectly spelled "Pozidrive", is an improved version of the Phillips screw drive. "Cam-out" is what happens when the rotational force of a screwdriver bit causes it to disengage the fastener and slip out. (1943). The number 10 screw is found often in construction projects and the 12 screw is used in heavy construction projects of all kinds. [34], A Robertson screw, also known as a square[35] or Scrulox screw drive, is specified as ANSI Type III Square Center and has a square-shaped socket in the screw head and a square protrusion on the tool. Phillips drive bits are often designated by the letters "PH",[10] plus a size code 0000, 000, 00, 0, 1, 2, 3, or 4 (in order of increasing size); the numerical bit size codes do not necessarily correspond to nominal screw size numbers.[3][13]. The ASTER recess was designed by LISI Aerospace[40] to provide a more reliable solution than the hexagonal recess for assemblies of composite structures on aircraft. Like the Phillips screwdrivers, Robertson drives also make use of a numbering system. A lot can be understood about a screwdriver bit drive system just by looking at the shape of its point. The design is often criticized for its tendency to cam out at lower torque levels than other "cross head" designs. Thanks for the comment. Similar security fasteners are also available for bicycle wheels and seats. ", "Improvements in or relating to screw threaded fasteners and drivers for use therewith", "Recessed head fastener and driver combination", "Screw head types / Product Guides / Service / Information & Services / England / Home Wiha | Screwdrivers L-Keys Bits Pliers Online Shop| Premium Tools for Professionals", "Unterschied zwischen Pozidrive und Superdrive", "Phillips, JIS, Pozidriv, SupaDriv and other screw drive types", "Supadrive allow a small angular offset between the screw and the screwdriver. [81] Phillips heads bits can be used to turn Pozidrive fasteners (although not optimally), but Pozidriv bits will ruin Phillips fasteners if mixed up. Since their introduction in the 1930's, improvements in power tools that allow users to set tools at fixed torque have encouraged production of new drive systems that reduce cam-out even further. By thinking about cam-out and the level of torque they need from a screwdriver bit, shoppers can choose the system that conserves bit wear (and therefore, expense) the best. Here's we've put together screwdriver sizes charts for the 6 most common screw head shapes. Receive money-saving advice and special discounts! A #0 is nice to have but I wouldnt consider essential. Spanner Sockets. The Phillips screwdriver has become the standard in many different countries. An external Torx screw has a projecting head in the shape of a Torx screwdriver bit (instead of a standard recessed cavity); a Torx socket is used to drive it. Because the heads must stand out from the surface they attach to, they are rarely available in countersunk or flush designs. Phillips bits are sized by simple, round numbers, such #1, #2, #3, etc. Pozidriv bits have a PZ marked on them along with five common sizes. One-handed use because of tight fit. The "slot" or "slotted" drive system is one of the oldest fastening systems, and it is the most simple. However, this design is not well-suited for installation by power tools, given that a power driver often slips out of the slot; this often causes damage to the screw and surrounding material. Hex bit sizes should match fastener sizes exactly. Correct, Ruben. The pentalobe screw drive is a five-pointed tamper-resistant system implemented by Apple in its products. Willi Hahn Corporation, dba Wiha Tools, is a wholly-owned subsidiary of Wiha Werkzeuge GmbH headquartered in Schonach, Germany. The design allows for higher torque application with reduced camming, slipping out and damaging the fastener.[59]. Because of their complicated shape, hex bit sizes must match fastener sizes exactly. The driving tool is called a "spanner driver" or "spanner screwdriver"[75] in the US, and a "pin spanner" in the UK. Square Recess Screwdriver Magnetic Square Screwdriver. I have never used a Robertson but I have read much about it and I have lamented for years about the awful slut, I mean slot head screw and the the commonly cammed out Phillips.