Plunge bit has four cutting edges per knife,.#rc-1084, (D) diameter: 3/4, (b) Cutting height: 30mm, (D) shank: 1/2, overall length (L): 3-D/8, replacement screw: 67115, replacement knives: rck-30, flutes: 2, RC-1084 insert carbide Straight 3/4 dia x 30mm x 1/2 inch shank