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 with timber during drilling. The wings ream a hole and then break off upon contact with the metal surface, allowing the thread to engage with the metal. They are equipped with a TORX(r) 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. This specific variant has a No.5 drill tip suitable for self-drilling heavy gauge steel up to 12.5mm. The size is 5.5 x 65mm, with a clamping thickness of 36mm and an effective thread length of 37mm. They come in a pack of 100.