Uxcell a15012000ux0523 Carpenter 1/4 Inch x 3/4 Inch 2 Flutes Round Shank Cove Box Router Bit Product Name : Cove Box Bit; Standard : 1/4" x 3/4";Radius : 9.52mm / 3/8" Cutting Diameter(Approx.) : 19mm / 3/4";Shank Diameter : 6mm / 1/4" Cutting Thickness : 12.7mm / 1/2";Total Length : 45mm / 1.8"