Hex head self-drilling screws, for joining roofing sheets to light section steel (Max. 5.0mm) without the need to pre-drill a hole. Exterior plating gives a reliable and durable corrosion resistant coating which resists 500 hours salt-spray" Thread Dia. mm: 5.5 Length mm: 19 Head Type: Hex Fixed Washer Dia. mm: 12.00 Point Type: Self-Drilling No.3 Socket Size mm: 8 Finish: Exterior (Silver Organic) Material: Case & Core Hardened Carbon Steel Effective Thread Length mm: 4 Max Drilling Thickness mm: 5.0Size 5.5 x 19 - 100 pcs Timco Metal Light Section Screws - Hex - EPDM Washer - Self-Drilling in Silver