Cobalt Drill Bit Set 19pce 1-10mmOverviewUltra-hard 5% cobalt steel. Use on alloy and hardened steel, cast iron, titanium and stainless steel. Always use cooling agent. Sizes: 1-10mm in 0.5mm increments. Loops 19 Piece 1mm 10mm Cobalt Drill Bit Set For Hardened Steels & Cast Irons in Metallics