Winged Roofing Screws. Timber To Steel. (For Light Section Purlins). Countersunk Head Screw. Timber To Steel Purlins. Head: Countersunk Torx Compatible Winged Self-Drilling Point. Finish: New 'Elementech' Coating For Superior Anti-Corrosion - Salt Spray Tested To 1000 Hours. Foc Torx Compatible Bit In Every Pack. Techfast Light Section Screw Will Fix Timber To Steel Thickness Between 1.5Mm To 4Mm. Self-Drilling Point Enables Improved And Speedy Insertion. Wings Create A Clearance Hole In The Timber Which Eliminates The Chance Of &Ldquo;Jacking&Rdquo; When Fixing. Designed Specifically For Fixing Timber Work To Steel Sections.PTDFORDIRTFCL4838