Flat countersunk head selfdrilling wood screws T15 hardened martensitic stainless steel 4x40

TORX (from the English word ‘torque’) is the registered word mark for a screw drive profile, the standard designation for which is ‘internal six-lobe’ (English: ‘six lobe, internal socket’). With the six-lobe internal socket, the screw and tool are subjected to less radial stress than with the traditional internal hexagon, and consequently suffer less damage. Torque is transmitted more directly via the radial parts of the tooth flanks rather than via the faces of the hexagon.

Stainless steel refers to alloyed or unalloyed steels that contain at least 10.5% chromium and less than 1.2% carbon. Colloquially, stainless steel is also referred to as stainless steel (NiRo), although not all stainless steel is the same as "stainless".