Starrett A4 615-242 Arbor & High Speed Steel Pilot Drill Bit For 14-30mm Hole Saws The Starrett A4 Arbor with 6.35mm (1/4\") high speed steel pilot drill and 6.5mm (1/4\") hex shank fits hole saw diameters of 14 - 30mm (9/16\" - 1.3/16\"). A set screw in the body allows for easy replacement of the pilot drill. Screw thread 1/2\" - 20.  FEATURES Compatible with hole saws of diameters from 32 - 210mm Fitted with a 6.35mm (1/4\") high speed steel pilot drill and 6.5mm (1/4\") hex shank Set screw in arbor body allows easy replacement of the pilot drill SPECIFICATION Pack Quantity: x1 Pc Part No: A4 615-242 Diameter / Shank Size: 6.5mm