There are a few hex and Torx key variants that differ slightly from the normal key design.
Security hex
A security hex key looks almost identical to a standard hex key with one exception: it has a small hole drilled into the end of the hex bar.
Security hex keys are designed for turning security hex fasteners. These fasteners have a small raised pin in the centre of the female hex recess. The raised pin prevents a normal hex key from locating into the female recess and turning the fastener.
The raised pin in the centre of the fastener head locates into the hole at the end of the security hex key. This allows the rest of the security hex key to locate into the female recess on the fastener head. Security hex keys often have chamfered edges but they are not made with ball ends.
Hex-Plus
Hex-Plus keys have a slightly different profile to standard hex keys. Instead of the sides being flat, they are slightly concave. This design is said to reduce wear of both the key and the inside of the fastener head, by increasing the size of the contact area the key has with the inside of the fastener head.
This increased contact area spreads out the internal stresses in both the fastener and Hex-Plus key and can reduce the chances of stripping and rounding occurring. In some cases, Hex-Plus keys can be used to loosen a fastener that has previously been rounded by a standard hex key.
Extractor hex keys
Extractor hex keys are designed for removing fasteners with stripped heads, that other hex keys can no longer turn.
They feature cutting edges on their corners that bite into the fastener head of stripped fasteners.
By biting into the fastener head, the cutting edges provide the grip needed to turn the fastener.
Security Torx
Just as a hex and security hex key look virtually the same a security Torx key looks almost identical to a standard Torx key with one exception: it has a small hole drilled into the end.
Security Torx keys are designed for turning security Torx fasteners. These fasteners have a small raised pin in the centre of the female Torx star recess. The raised pin prevents a normal Torx key from locating into the female recess and turning the fastener. Instead, a specialist security Torx key is required to turn these fasteners.
The raised pin in the centre of the fastener head locates into the hole at the end of the security Torx key. This allows the rest of the security Torx key to locate into the female recess on the fastener head in order to turn it.
Security Torx keys are sized in the same way as normal Torx keys and use the same sizing designation of the letter T followed by a number ranging from T1 (smallest) to T100 (largest). For more information on sizes see What Torx and hexagon key sizes are available?
Torx Plus
Acument, who now own Camcar Textron, released Torx Plus in 1990, when the original patent for Torx was expiring. Torx Plus keys have a squarer shape to the six pointed ends of their star shape. This, it is said, allows them to transmit higher torque to a fastener whilst reducing wear on the key and inside the fastener head.
The squarer shape and stricter design tolerances of Torx Plus increases the contact area between the Torx Plus driver and fastener when compared with a standard Torx driver and fastener. As stress is force divided by area, more force can be transmitted and the internal stresses reduced, thus wear is reduced in both the Torx Plus key driver and the head of the fastener.
Torx Plus keys are also referred to as internal plus keys, and it is from this that the often-used size designation of IP comes. The sizes of Torx Plus keys range from IP1 (smallest) to IP100 (largest); sometimes these are listed as 1IP or 100IP.
Tamper resistant Torx Plus
The tamper-resistant Torx Plus is a security fastener and driver system. It has the same benefits of increased torque transfer from driver to fastener, and reduced wear of driver and fastener that Torx Plus has.
Whilst the points of the star have the same individual shape as Torx Plus points, there are only five points on the star of tamper resistant Torx Plus keys and fasteners. Just like security Torx, tamper resistant Torx Plus have a pin in the centre of the fastener head’s recess that locates into a hole at the centre of the tamper resistant Torx Plus key.
The combination of the five point star shape and centre pin design provides increased security as the fasteners are extremely difficult to remove without the correct tamper resistant Torx Plus key. Tamper resistant Torx Plus keys and fasteners are only supplied to original equipment manufacturers (OEMs) and authorised service personnel, adding to the security provided by their use.
There is no official designation for tamper resistant Torx Plus keys, although some sets are sold with the initial TS or IPR followed by the size.
