Hymnorq Cobalt Drill Bits 15Pc Set, Metric Size 1.5-10Mm In Indexed Case, M35 COBALT STEEL - Manufactured from M35 cobalt steel, with molybdenum and cobalt added to creates a hardened alloy, measuring Rockwell hardness up to 67, for much faster cutting and extra longer life span, with up to twelve times when compared with an average HSS drill bit. 135SPLIT POINT - the 135quick-cut split point are self-centering and able to penetrate metals quickly with less pressure, prevent bits from "walking and wanding". Easy cutting without need of center punch. 15PC METRIC SET - The set includes 15pcs of M35 cobalt steel twist drill bits: 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7 mm, 8 mm, 9 mm, 10 mm. Well organized in a plastic indexed storage case for easy transport to your worksite. FOR METALWORKING - Particularly successful in cutting through hard metals(hardness less than HRC38) such as stainless steel and cast iron, although they can be used for softer materials like copper and aluminium, too. Not for hardened steel / high carbon steel. Try to adjust the RPM when it fails to penetrate. DOWNLOADABLE USER GUIDE - We've summed up some tips of drilling metals, including a RPM chart for several common metals, based on our reviews and some articles on the internet. In most cases, our customers would get a much better result with these tips. Welcome to download.