The Irwin Metric HSS Cobalt Drill Bits are perfect for drilling stainless steel and other high alloy steels. They have 5% cobalt for higher heat and abrasion resistance and a heavy-duty web construction for strength and durability. The 135 split point begins drilling immediately, minimising bit walk and they are manufactured to DIN 338 Standards. The IRW10502520 HSS Cobalt Drillbits are supplied in a pack of 10 and have the following dimensions: Diameter: 4.0mm. Total length: 75mm. Working length: 43mm. IRWIN Hss Cobalt Drill Bits (10) 4.0Mm Ol:75Mm Wl:43Mm in Gold