THW metal cavity fixing 1260170 (set of 50 pieces) comes with a screw (length: 38 mm, diameter 4.2 mm) and is excellent for installations in plasterboard materials To be used for lightweight installations in board materials ranging from 6 to 13 mm thickness, excellent for porous and thin materials The shape of THW prevents it from rotating No pre drilling needed, just hammer in Material: Steel, yellow-chromated (THW), electroplated (screw) Installation: Hammer the cavity fixing in place, No pre drilling needed. Mount the fixture with the included Phillips PH2 screw (cross-recessed)