Forgefix self tapping screw pozi csk zp forgefix stpp28zp these forgefix pozidriv self tapping screws are zinc plated for increased resistance to corrosion their pan head with a flat under head surface makes the screw ideal to lay flat on sheet material of all types thus reducing deformation the screws tap their own thread in a pre drilled pilot hole in sheet metal the screws are single threaded to resist pull out ideal for use in many diy ironmongery engineering electrical and plum