These Forgefix TechFast Hex Head Screws are designed specifically for fixing cladding and sheet metal to timber frame work. They have a Hex slash point head and are self-drilling for speedy insertion. The screws have a rubber washer beneath the aluminium flange which expands under pressure and forms a permanent weather seal. They are zinc plated and have an ‘Elementech’ coating for superior corrosion resistance, which has been salt spray tested to 1,000 hours.