This Evolution Hex Washer Head Self-Drilling Tek 1 Stitching Screw is designed for stitching cladding panels, with a 16mm Bonded EPDM Washer. It has a coarse thread form (Tek 1) and is made from carbon steel with a AISI C1022 material grade, with an effective thread length of 18mm. The drilling capacity is 0.8-2.5mm and the recommended drill speed is 1500-2500 RPM.