****** - Verified Buyer
4.5
They work great for what I do with them, but I'm not drilling through really hard stuff. Usually, M42 drills will have some sort of designation like "m42" or ''co" stamped in the drill to indicate they are cobalt. These only have "HS" indicating high speed steel. Who knows if they are cobalt. I suggest if you are drilling through hardened material go with m42 through a trusted supplier like mcmaster carr.
