Metallics NHSDBG21E High-Speed Twist Drill Bit 21" 3-1/4" SplPt Blk Ox (1pc)

One bit per order. The NHSDBG21E high-speed twist drill bit ships as a single piece in a pouch, so if you want spares on the truck you need to order multiple.

A split point self-centers and starts cutting without walking, so you can begin a hole in a stud or top plate without a pilot or center punch. That matters on a long bit like the NHSDBG21E, where any wander at the entry point gets magnified over the length of the hole.

The 21 inch length is for reaching through framing from one side of a wall or ceiling bay, the way an electrician drills a run of studs or bores through a plate from below without opening up the assembly. For a single 1-1/2 inch stud a standard jobber bit is plenty; the long bit earns its keep when you need depth or standoff from the work.

Black oxide on an HSS bit cuts friction and helps hold cutting lubricant, and it adds some corrosion resistance for a bit that lives in a pouch in a truck. It's a surface treatment, not a carbide or cobalt upgrade, so for repeated drilling in heavy steel you'd step up to a harder bit; for wood framing and light metal the NHSDBG21E's black oxide HSS is the normal choice.

Order by the Metallics part number NHSDBG21E. That is the 21 inch high-speed steel split-point bit with a black oxide finish, supplied one per pouch. There is a single configuration under that number, so there is no diameter or length option to specify separately.