Hex washer head self drill with EPDM rubber metal beaked washer for metal roofing and siding The hex washer head self drill come with a drill point (TEK) for attaching metal roofing and siding panels to metal stud framing. These screws come in #8, 10, 12 and 14 diameters and come as long as 6" long. They are normally fully threaded minus the drill point. Drill points come in TEK #2, 3, and 4-5. TEK self drills are based on the thickness of the metal you are penetrating, the typical 25 to 16 gauge will use a TEK 3 and 14 gauge and below will require TEK 4-5. The EPDM (Ethylene Propylene Diene Monomer) rubber which has a wide range of application. This is the best rubber for metal building and siding applications to stop water from entering the building with long life spans. The fasteners and metal backed washer is made from 410 stainless steel.