Used for attaching metal to heavy section steel (Max. 12mm) without the need to pre-drill a hole. Hardened carbon steel drill tip fused on to an A2-304 Austenitic Stainless Steel body" Thread Dia. mm: M5.5 Length mm: 38 Head Type: Hex Fixed Washer Dia. mm: 11.00 Point Type: Self-Drilling No.5 Socket Size mm: 8 Material: Bi-Metal/A2-304 Stainless Steel/Carbon Steel Effective Thread Length mm: 17 Max Drilling Thickness mm: 12.0Size 5.5 x 38 -100 pcs Timco Metal Heavy Section Screws - Hex - Self-Drilling - Bi-Metal Exterior in Silver