Tough and hardened for universal use. 1/4" Hexagon suitable for wrenches as per DIN ISO 1173-D 6.3
Premium bits for TORX socket screws. 
Borehole to prevent unwanted unfastening of safety screws. They contain a pin that protrudes into the drive profile so that the normal TORX tools cannot be used.
Features

Securing pin
Torx bit with a borehole on the output side
1/4" Hexagon drive