Forgefix TechFast Timber to Steel CSK/Wing Screws are designed for joining timber to steel frame buildings. These screws feature breakaway wings that create a clearance hole, preventing the thread from engaging the timber during drilling. As the wings ream a hole, they break off upon contact with the metal surface, allowing the thread to engage with the metal. They incorporate a TORX compatible insert for enhanced power transmission and have recessed ribs for improved countersinking. The screws are fire and corrosion resistant and comply with EU Safety, Health, and Environmental requirements. Specifics include a size of 5.5 x 80mm, a clamping thickness of 56mm, an effective thread length of 57mm, and a pack size of 100. The No.5 drill tip is suitable for self-drilling heavy gauge steel up to 12.5mm.