M35 Cobalt Steel - Manufactured from M35 cobalt steel, with molybdenum and cobalt added to creates a hardened alloy, measuring hardness up to 67, for much faster cutting and extra life span, with up to twelve when compared with an average HSS drill bit. No Center Punch Needed - the 135 quick-cut points are self-centering and penetrate quickly with less pressure. Will not "walk" or "wander" For Stainless Steel - Particularly successful in cutting through hard metals such as stainless steel and cast iron, although they can be used for softer materials, too. Not for hardened steel / high carbon steel. Try to adjust the RPM when it fails to penetrate. 50pcs Set - The set includes 50pcs of metric M35 cobalt steel twist drill bits: 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 10pcs of each size. Color: gold Material: Cobalt steel alloy Cobalt drill bits are not made of pure cobalt, but rather a steel alloy with certain percent cobalt. The 5-percent alloy is known as M35 grade. The cobalt increases the strength of the steel and makes it more heat-resistant. For Drilling Stainless Steel This M35 cobalt steel drill bits are particularly successful in cutting through hard metals such as stainless steel and cast iron, although they can be used for softer materials, too. 135 Degree Split Point The flater the drill, the smaller the chip width. This means less force required to remove metal, compared with lower angles like 90 and 118. This is important on hard stuff, because your power requirements are already more than mild steel, so making the chip load less helps. It also reduces heat since less surface area is generating the cut. Not Suggested for Hardened Steel, High Carbon Steel and Steels Blended with Impurities Cooling Liquid Required Please use with cooling liquid to prolong the working life of the drill bits and to avoid overheating and breakage. About Breakage Please be careful when you drill holes with shese needle-like small bits. They're more likely to break than larger ones. Package Includes : 10PC X 1.0MM drill 10PC X 1.5MM drill 10PC X 2.0MM drill 10PC X 2.5MM drill 10PC X 3.0MMdrill