Amazon.com has a star shaped screwdriver and a small star screwdriver.

A trademark type of screw drive characterized by a 6-point star-shaped pattern was developed in 1967.The drive's generic name is star, as in star screwdriver or star bits.ISO 10664 is the generic name used by the International Organization for Standardization.This is sometimes abbreviated as 6lobe in databases and catalogs.The improved head profiles are called Torx Plus, Paralobe and ttap.

There are screwdrivers on automobiles, motorcycles, bicycle brake systems, hard disk drives, computer systems and consumer electronics.They were sometimes used in applications requiring resistance, since the drive systems and screwdrivers were not widely available.In construction industries, trex screws are becoming more popular.

The design of the Torx head screws makes them better at resisting cam-out.The tendency ofPhillips drivers to cam out under excessive Torque has been listed as a feature preventing damage to the screw-head or driver.This change was made possible by the development of better automatic screwdrivers.Torque-limiting driver designs do not rely on the tool to slip out of the screw head when the desired Torque is reached.

The Torx design allows for a higher Torque to be exerted than a similarly sized conventional head without damaging the head or the tool.The diagram shows the interaction between the male and female components of a drive.For clarity, the clearance between the components is exaggerated.

The six points of contact between the two components are represented by a green circle.A radial force is generated which tends to "burst" the female component and crush the male component because the plane of contact is not parallel to the circle.If the radial force component is too strong for the material, it will cause the corners to be rounded off or split in two.The force is proportional to the angle between the green circle and the plane.

The potentially damaging radial force for a given Torque is much lower for the Torx type of design, as the angle is closer to 90.The property allows the head to be smaller for the same required Torque, which can be an advantage in applications where space is limited.

The capital letter "T" is followed by a number ranging from T1 to T 100.Some head sizes are abbreviated "TX" or "Tx" in front of the number.A smaller number indicates a smaller point-to-point dimensions of the screw head.T10, T15, and T25 are common sizes, while T35, T47 are used for specialized purposes.Only the proper driver can drive a specific head size.The number of bit sizes required is reduced with the use of the same series of drivers.

The capital letter "E" is followed by a number ranging from E4 to E44.The E numbers are different from the T numbers of the same size.[6]