The Starrett Hole Saw arbor supplied with 6.35mm (1/4-inch) carbide tipped pilot drill. Shank size 8.75mm (11/32-inch). Screw thread 1/2-inch-20.
The Starrett XA1 Hole Saw Arbor has a Carbide Tipped Pilot Drill that is necessary when using Carbide and Diamond hole saws. The XA! has a 11/32" hex shank for use in 3/8" chucks and fits hole saws from 9/16" to 1 3/16". A set screw in the body allows for easy replacement of the pilot drill.