The 631 is a 7-piece nut driver set designed for professional use. This set includes seven nut drivers with 3-inch (76.2 mm) hollow shafts, covering sizes from 3/16" to 1/2". Each driver features a premium chrome-plated shaft for corrosion resistance and a Cushion-Grip handle that provides greater torque and comfort. The handles are color-coded with Tip-Ident markings for quick size identification, and the tools meet or exceed applicable ASME/ANSI and MIL specifications.