SPECIFICATIONS Diameter: 1- 3/8" Cutting Length: 5/8" Radius: 3/16" Shank Diameter: 1/2" Total Length: 2-3/4" Bearing: 3/8" x 3/16" x 1/8" (Replacement model #R166ZZ1) Craftex Blue Tornado bits are CNC machined to have perfect balance and leave a smooth finish. All bits are manufactured from 4140 & 5140 steel and are put through a special heat treatment process to ensure proper hardness and tensile strength to prevent bending or breaking.