A tamper-proof Torx screw has a pin standing in the centre of the recess, and a standard Torx driver cannot enter it at all. This is the complete list of 7 tamper-proof Torx drivers in the range, with part numbers.
What the pin does
The recess is an ordinary Torx star with a solid post in the middle. A tamper-proof driver is the same star form bored down its axis to clear that post, so it engages the lobes exactly as a standard driver would while the pin passes harmlessly up the middle. The security is entirely a matter of the tool being uncommon — mechanically the fastener drives just like a Torx screw once you have the right driver in your hand.
Where these turn up
Anywhere a manufacturer would rather the public did not go: electrical enclosures, public-facing equipment, appliance casings, vending and gaming machines, and increasingly on vehicle trim and electronics. They are also common on anything with a safety interlock, where the intent is to make opening a housing a deliberate act rather than an idle one. For anyone servicing that equipment they are ordinary fasteners that simply need the correct driver.
All 7 tamper-proof drivers
| Tip size | Blade length | Hex bolster | Teng part number |
|---|---|---|---|
| TPX10 | 100 mm | No | MD610TPN |
| TPX15 | 100 mm | No | MD615TPN |
| TPX20 | 100 mm | No | MD620TPN |
| TPX25 | 100 mm | No | MD625TPN |
| TPX27 | 100 mm | No | MD627TPN |
| TPX30 | 100 mm | No | MD630TPN |
| TPX40 | 100 mm | No | MD640TPN |
Where this list comes from
Every row is read from the live Teng Tools USA catalogue on the day this page was generated — product record, part number and size taken from the record itself, never transcribed from a printed catalogue or inferred from a pattern. Sizes use the TPX designation as marked on the tool; blade length is read from the product record. A size that has been discontinued disappears from this list rather than lingering as a part number you cannot order, which is the failure mode of every static spec sheet.
Do not drill the pin out
The common improvisation is to break or drill the centre post so a standard driver fits. It sometimes works and it is a poor trade: the post is often the same hardened steel as the head, drilling it usually damages the lobes on the way, and once it is gone the fastener cannot be driven to proper torque on reassembly. Where the head survives at all it is left as a damaged Torx recess, which is a worse fastener than the one you started with.
Drivers are in screwdrivers; tamper-proof keys and bits are in hex and TX keys.