1. The M35 drill bit is made of cobalt high speed steel, contain 5% Cobalt, high hardness, fast cutting speed, improve wear resistance, more durable than ordinary high speed steel drill bit.2. The cobalt drill bit can be used to harden materials. Such as hard metal, stainless steel, copper, aluminum, cast iron, plastic and wood, can also be used for softer materials.  Not suitable for glass or ceramic materials.3. 135° Quick-cut split point, round straight shank, prevent walking, make drilling accurate and faster.  Fully ground spiral groove design, quickly removes debris, reduces friction and heat, ensures smooth chip movement.4. This series are small drill bits, please note the size before you buy. Suggest speed 100-800r/min.