I Finish and drill holes in 3/8 A-2 tool steel at a 30 degree angle so I start with an interrupted cut. and end of cutting. I was lucky enough to get 90 holes from a carbide bur. Through stainless steel I was lucky enough to get 40 holes. This 3/16 cutter made 180 holes (60 through stainless steel) and still works. I don't know how long it will last, but so far it has done twice as much as any other editor. I don't buy China. I usually buy from an industrial supplier. I tried them just for a smile and I'm glad I did. The faucets are also exceptional. I'm addicted to Kodiak!