Torx

Torx is a screw and bolt head with a six-lobed, star-shaped recess, sized with a T number such as T25 or T30. Because the driving surfaces are almost vertical, the bit transfers torque without pushing itself out of the head. This 'cam-out' effect is what often strips Phillips and flat-blade screws.

On motorcycles, Torx bolts are common on brake discs, fairing panels, dashboards and engine covers. External Torx (E-Torx) and tamper-proof versions with a centre pin also exist.

Use the exact size and a good-quality bit, and push it fully into the recess before turning. A slightly too small bit will round the head. For tight brake disc bolts, clean the recess first and use a bit on a ratchet or torque wrench, not a screwdriver.