These Forgefix TechFast Roofing Screws are designed for use in joining timber to steel and for heavy section purlins They have a Torx compatible countersunk head to sit flush to the surface The self-drilling point enables speedy insertion and the wings create a clearance hole in the timber to eliminate the chance of jacking when fixing The screws are zinc plated and have an Elementech coating for superior anti-corrosion which has been salt spray tested to 1000 hours These heavy section roofing screws are suitable for fixing timber to steel thicknesses of 60mm to 125mm Each pack is supplied with a free Torx compatible bit