Boring Head Set, 75 mm outer diameter, with MK4 Shank and chisels. The boring head has a diameter of 75 mm. Also includes the set is a 5 piece chisel set (hard metal with a massive 20 mm Shaft) and Allen key for tool change. Locating hole: 20 mm. Centre Distance between the holes: 24 mm. Transverse hole: 20 mm. Verfahrweg: 25 mm. Minimum bore diameter: 10 mm. Maximum Bore Diameter: 220 mm. Mounting thread: 11/2 x 18 "