Review on 🔩 Bosch Cobalt Metal Piece CO21 by Alex Mitra

Waste drill bits used to try to drill holes in steel for a custom garden tractor hitch and couldn't keep them past a few holes even when starting small and 3 increased Fold to 3/8 inch hole. We're talking hardened or stainless steel, but they're no better than standard HSS bits. Nowhere have I seen a hardness rating on them. Found from the same brand at Menards for a few bucks more, the m42 shows what is about the hardest part you can buy.