GearWrench 388710N 5/16 x 24 NF Taper Tap The GearWrench 388710N 5/16 x 24 NF Taper Tap features tapered cutting edges, which give a less aggressive cut than plug taps in small diameters. Manufactured from carbon steel, the GearWrench 388710N 5/16 x 24 NF Taper Tap has clear laser-etched size markings for easy identification.