Wera Tamper-proof (Security) Torx Plus Bits have a more elliptical profile than the traditional round profile that the standard Tamper-proof Torx bits have.  This makes it possible for the Torx Plus tools to increase the 6 flanks that transfer the torque between the tool and the screw.  The force applied by the operator is distributed across a larger surface area allowing more torque to be transferred and extends the service life of the Torx Plus Bit and the screw.  The center bore hole allows for fastening and unfastening of Tamper Proof Torx Plus screws.

867/1 IPR TORX PLUS Insert Bits (Tamper-Proof)

867/4 IPR TORX PLUS Power Bits (Tamper-Proof)