From Forgefix
Features/Benefits Used for joining metal roofing sheet panels together. Self-Drilling in Roofing Sheet Steel up to 2.5mm. 8mm Hex Head. Smaller No. 1 drill tip can drill through two sheets then engage the threads to clamp the sheets together under the head. Fire and corrosion resistant, protected by Elementech corrosion resistant coating, salt spray tested to 1000 hours. Complies with EU Safety, Health and Environmental requirements.