The Starrett A2 Quick Hitch Arbor with 6.35mm (1/4") high speed steel pilot drill and 11mm (7/16") hex shank, fits hole saw diameters 32-210mm (1.1/4" - 8.9/32"). A set screw in the body allows for easy replacement of the pilot drill. Quick Hitch arbors permit instant change of hole saws without tools or removing the arbor from the chuck. Screw thread 5/8" - 18.