Milwaukee Tool 48-89-2331 15 Piece Cobalt RED HELIX, Kit

Yes. The 48-89-2331 is a 15 piece cobalt set built for drilling the hardest materials, stainless steel included. Cobalt holds its edge at the higher temperatures stainless generates, and the chip breaker on these bits cuts heat buildup while you drill. Milwaukee rates them at up to 10 times the life of black oxide bits.

They're made not to. The shanks on the 48-89-2331 bits use Milwaukee's Secure Grip shank, which is there specifically to stop the bit spinning in the chuck under load. That matters most on the larger bits in the set, where torque is highest and a round shank is most likely to slip.

Not usually. These bits are ground with a 135 degree split point, which starts cutting on contact instead of skating across the surface. On slick stainless or a curved surface a punch mark still helps, but for flat plate and general fabrication the split point is enough to keep the bit where you put it.

It's a 15 piece drill bit set, sold as a kit under part number 48-89-2331. One order covers the full range of sizes in the kit, so it's the piece to buy when you're stocking a service truck or an MRO crib rather than replacing one broken size.

Black oxide is fine for wood, plastic and mild steel, and it costs less per bit. Go cobalt, like the Milwaukee 48-89-2331 kit, when the work includes stainless, hardened steel or anything else that work-hardens and cooks a standard bit. Milwaukee puts the life difference at up to 10X over black oxide. Most shops carry both and save the cobalt for the hard stuff.

It clears chips faster. The RED HELIX flute geometry pulls swarf up and out of the hole quickly, which is what keeps a cobalt bit from packing up and overheating in deep or gummy material like stainless. Paired with the chip breaker, it's the reason these bits stay sharp longer than a standard twist bit.