Ground Thread / For tapping left hand threaded holes. / Includes 1 of each / 1 Taper Taper (7-10) Thread Chamfer for easier starts & less torque. / 1 Plug (3 - 5) Thread Chamfer, most versatile choice for through or blind holes. / 1 Bottoming (1- 2) Thread Chamfer, designed for threading near the bottom of blind holes.