Hex head self-drilling screws, for joining roofing sheets to light section steel (Max. 5.0mm) without the need to pre-drill a hole. Fire Classification: A1" Thread Dia. mm: 5.5 Length mm: 45 Head Type: Hex Fixed Washer Dia. mm: 11.00 Point Type: Self-Drilling Socket Size mm: 8 Finish: Zinc Material: Case & Core Hardened Carbon Steel Effective Thread Length mm: 34 Max Drilling Thickness mm: 5.0Size 12 x 1 3/4 - 500 Pieces Timco Metal Construction Light Section Screws - Hex - Self-Drilling - Zinc in Silver