Set includes 4 x plug cutters: 6.35mm (1/4″), 9.50mm (3/8″), 12.7mm (1/2″), 15.8mm (5/8″) and 4 x chamfered plug cutters: 12.7mm (1/2″), 15.8mm (5/8″), 19mm (3/4″) and 22.2mm (7/8″). 10mm (3/8″) round shank. Strong carbon steel construction. Supplied with wooden storage case.