These ForgeFix Pozidriv Self-Tapping Screws have countersunk heads and are made from A2 stainless steel, which will not corrode, rust or stain with ordinary water like other steel does. The fixings tap their own thread in to a pre-drilled pilot hole in sheet or solid material. They are single threaded to resist pull-out. APPLICATION: Ideal for use in many DIY, ironmongery, engineering, electrical and plumbing applications.