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. The TFHT6325 TechFast Hex Head Screws have the following specifications: Size: 6.3 x 25mm. Box quantity: 100. FORTFHT6325