4 Piece Hollow Chisel & Auger Bit Set. A set of 4 imperial sized mortice chisels, with full length windows for fast chip ejection. Supplied in a wooden storage case. Charnwood MCCSET4 Specification Chisel Size: Chisel Shank size: Max. Cutting Depth: Auger Shank Diameter: Auger Length: 1/4″: 3/4″: 40mm: 4mm: 160mm: 3/8″: 3/4″: 50mm: 6mm: 200mm; 1/2″: 3/4″: 70mm: 9mm: 215mm: 5/8″: 3/4″: 70mm: 12mm: 225mm Mortice Chisels are available in various shank sizes, which needs to be matched to the machine you are using. This set is 3/4″ shank. Some morticers are supplied with alternate chisel bushes to allow different types of chisels to be used.