Three chemically-combined anti-corrosion layers give Kreg"s Blue-Kote screws up to 400% more weather resistance than zinc-plated screws. They"re an ideal choice for garden and patio furniture, as well as for general exterior construction. Self-tapping screw tips make for easy driving. Case hardened steel won"t bend or break, and the deep-seated #2 square drive heads eliminate "cam out," ensuring a tight, solid joint.