By design, Torx head screws resist cam out better than Phillips head or slot head screws. [1] Whereas the tendency of Phillips drivers to cam out under excessive torque has been listed as a feature preventing damage to the screw-head or driver, [5] Torx heads were designed to prevent cam-out. The development of better torque-limiting automatic screwdrivers for use in factories allowed this change. Rather than rely on the tool to slip out of the screw head when a desired torque level is reached (which risks damage to the driver tip, screw head, or workpiece), torque-limiting driver designs achieve a desired torque consistently. Construction Range Overview (Fasteners: Introducing the AW Drive System, p. 3)" (PDF). Würth New Zealand. 2016. The following is a Torx Bit Sizes Chart for Internal Torx. Two dimensions are important with respect to Torx screws. They are Point to Point and Diameter of the screw threads. Torx Size The most common sizes of a Torx screw are T10, T15, and T25. There are also specialized Torx sizes, including T47, T55, T60, and T65. These are used in certain circumstances, but they are not as common as the T10, T15, and T25. a b c d e "Chart of Torx fasteners and tools". Wiha Tools USA. Archived from the original on 2015-12-26 . Retrieved 2012-01-14.

Like all other fasteners, even Torx screws are available in different sizes. They follow a special ‘T’ sizing for the internal Torx an ‘E’ sizing for the external Torx. The size of the screwdriver or the drive bit must match with the size of the Torx screw. The Torx Plus drive system is another variation of the Torx. It is also known as External Plus. The lobes are more square than the original design. This design allowed for higher torque on the head. The Torx Plus also has five-lobed tamper-resistant variants. This design requires the right tools. Technical Information on Fasteners: Design recommendations 11.1 Inside drives for screws – AW drive (AW-Antrieb)" (PDF). Adolf Würth GmbH & Co. KG . Retrieved 2 March 2017.Torx (pronounced / t ɔːr k s/) is a trademark for a type of screw drive characterized by a 6-point star-shaped pattern, developed in 1967 [1] by Camcar Textron. [a] A popular generic name for the drive is star, as in star screwdriver or star bits. The official generic name, standardized by the International Organization for Standardization as ISO 10664, is hexalobular internal. [2] This is sometimes abbreviated in databases and catalogs as 6lobe (starting with the numeral 6, not the capital letter G). Torx Plus, Torx Paralobe and Torx ttap are improved head profiles. [3] The TORX(r) drive system has several benefits, including an easy solution to a common fastener problem, higher productivity, and enhanced reliability. You can also reduce total assembly costs by using the TORX(r) Drive System. SAE vs metric equivalents

Tamper-Resistant TORX PLUS Drive System" (PDF). Textron Fastening Systems. Archived from the original (PDF) on 2006-11-10. Unlike other screwdrivers, Torx fasteners are made to be resistant to cam-out. This is a type of tampering that occurs when a torque is applied to a screw that exceeds its limit. The Torx bit creates a round hole to prevent this from occurring. For example, if you have a screw with TX size, then you have to use a Torx Screwdriver or drive bit of TX size only. The most common sizes are T10 and T25. The head height is 0.062 inch (1.6 mm). The head diameter is 0.50 inch (1.27 cm). Some other specialized sizes include T55 and T27.Torx screws are commonly found on automobiles, motorcycles, bicycle brake systems ( disc brakes), hard disk drives, computer systems and consumer electronics. Initially, they were sometimes used in applications requiring tamper resistance, since the drive systems and screwdrivers were not widely available; as drivers became more common, tamper-resistant variants, as described below, were developed. [4] Torx screws are also becoming increasingly popular in construction industries.