Uxcell a14111000ux0045 Marble 31mm Diameter Bullnose Diamond Profile Wheel Router Bit Gold Tone Product Name : Diamond Profiler outer Bit; Material : Diamond; Cutting Radius : 8mm/ 5/16" Shank Diameter : 12.7mm / 1/2";Bearing Diameter : 13mm / 1/2" Cutting Depth : 12.7mm / 1/2";Overall Diameter : 31mm / 1 1/4"