TechFast Timber to Steel CSK/Wing Screw No.3 Tip 4.8 x 38mm Box 200 - ForgeFix TFCUWWSD55135H, Forgefix TechFast Timber to Steel CSK/Wing Screws are used to join timber to steel frame buildings. The screws are fitted with breakaway wings that create a clearance hole to protect thread from engaging timber when drilling through. Breakaway wings will ream a hole, then break-off when they contact the metal surface to be drilled. The thread will then engage with metal. They have a TORX® compatible insert for a higher transmission of power. With improved countersinking from recessed ribs. Fire and corrosion resistant. Complies with EU Safety, Health and Environmental requirements.These Forgefix TechFast Timber to Steel CSK/Wing Screws have the following specification: Size: 5.5 x 135mmClamping Thickness: 106mmEffective Thread Length: 107mmPack Size: 50Drill Tip: No.5 No.5 drill tip for self-drilling heavy gauge steel up to 12.5mm ForgeFix TechFast Timber to Steel CSK/Wing Screw No.5 Tip 5