These Forgefix TechFast Hex Head Roofing Screws are designed for fixing cladding and sheet steel to light section steel purlins of between 1.2mm and 3.6mm. The screws feature a hex head, are self-drilling, and include a rubber washer that expands under pressure to form a permanent weather seal. They are zinc plated and have an Elementech coating for superior corrosion resistance, tested to 1,000 hours in salt spray. This variant has an 8mm hex head, size 5.5 x 32mm, and comes in a pack of 100.