Self drilling screws, also known as TEK screws, have a tip to cut through material and eliminate the need to drill a pilot hole. An indented hex washer head offers advantages of hex head, plus greater protection to mating surface. Stainless steel 400 gives these screws the added benefits of higher strength and wear resistance. The passivated finish makes them much more resistant to corrosion than the original finish. These screws are typically used in metal to metal applications.