Product details: This self-drilling screw is used in wood, fiberglass, and metal, and it possess a drill point enabling it to drill its own hole in thin gauge steel. The sharp threads create their own mating thread when drilled into the material. No pre-drilled pilot holes are necessary. MULTI-MATERIAL FUNCTION: Ideal for use in wood, fiberglass, or metal SELF-DRILLING POINT: Together, coarse screw threads and a self-drilling point design eliminate the need for a pilot hole EXTERNAL HEX DRIVE: Offers controlled traction with a socket or wrench CORROSION-RESISTANT FINISH: Zinc plating offers moderate protection against rust and corrosion Zinc-plated for moderate corrosion resistance 25 zinc screws per pack