Metallics NHSD7E High-Speed Twist Drill Bit 7" 3-5/8" Blk Ox (1pc)

One bit per package. The NHSD7E is a single-piece item supplied in a pouch, so if you need spares on a job you order multiple units.

The bit is stated at 7 inches and 3-5/8 inches. On a twist bit of this style those two numbers are the overall length and the cutting portion, so your usable depth of cut is governed by the shorter 3-5/8 inch figure while the remaining shank length is what clears the chuck and the obstruction you are reaching past. If you need to bore all the way through a doubled-up plate deeper than the cutting length, step up to a longer electrician's bit.

Black oxide on the NHSD7E is a surface treatment over high-speed steel that reduces friction and helps resist rust in a damp truck or gang box. It is a coating, not a carbide tip, so the bit is intended for drilling metal and wood, not masonry or concrete.

Yes, it is carried as an electrical-trade drilling item and the length suits rough-in drilling through framing and sheet metal for cable and raceway runs. It is a bare twist bit only, so chuck adapters, extensions, or hole saws for larger openings are separate purchases.