3/4" End Mill Cutter Adapter Holder Bridgeport R8 Shank Adaptor Milling Cutting 3/4" End Mill Adapter Bore: 3/4" ; Drawbar Thread: 7/16"-20 Hardened and Ground; Made for high quality steel forgings Precision ground concentric; Ground shank and hole, heat treated for double accuracy Quantity: 1 ; Weight: 2 lbs