Metallics HSSC21E Drill Bit HD Cobalt St 135d SplPt 25/64" 5-1/8" YLW (1pc)

Yes. Cobalt high speed steel holds its edge at the higher temperatures you get cutting stainless, cast iron and hardened plate, where a plain HSS or black oxide bit dulls or burns. The 135 degree split point starts on its own without a center punch and resists walking on hard, smooth surfaces. Run it slow with cutting fluid and steady pressure; backing off to let the bit cool is what kills cobalt bits fastest.

It is a straight shank bit, so it chucks into any standard three-jaw drill chuck. At 25/64 diameter the shank exceeds 3/8, so you need a 1/2 inch capacity chuck, not a 3/8 inch drill/driver. A 1/2 inch magnetic drill or a corded 1/2 inch drill is the right tool for it.

One bit per pouch. It is a single-piece replacement item, so if you are burning through one size on a repeat job you order that size by the piece rather than replacing a full index.

The gold-yellow cast on the HSSC21E is the cobalt alloy's own surface color, not a coating that wears off like black oxide or titanium nitride. On the job it is mostly a sorting aid, since cobalt bits in a mixed pouch collection are easy to pick out from plain HSS by color.

Cobalt is alloyed through the body of the bit rather than surface treated, so the HSSC21E can be reground and keep its cutting properties. Regrinding the 135 degree split point correctly takes a drill point grinder; a bench grinder freehand will give you a standard point that no longer self-centers.