The Evolution Hex Head Self-Drilling Tek 5 Screws are designed for fixing cladding/roofing applications to hot/cold rolled purlins/rails, with a 16mm Bonded EPDM Washer. They have a single, fine thread form (Tek 5) and are made from carbon steel with a AISI C1022 material grade. The drilling capacity is 4.0-12.5mm and the recommended drill speed is 1500-2500 RPM.