4.2mm Drilling Dia HSS Cobalt Metric Spiral Twist Drill Bit Rotary Tool 6pcs

This product is made of?high?speed steel and cobalt material. After using full grinding ?process it has stronger cutting ability and longer service life. Suitable for processing non-ferrous metals (such as copper and aluminum) non metallic and ferrous metals (such as iron steel and stainless steel). Straight shank works in both keyed and key-less drill chucks. The advantages of full grinding drill bit:High geometric precision strong cutting ability. Smooth surface finish long service life. Wider using range (rough processing finishing semi finishing) and comes with edge clear function make processing products have better surface finish.