CMT 230.224.08 Box and Finger Joint Set, 8-Inch Diameter by 24 Teeth FTG Grind with 5/8-Inch Bore Excellent and precise cut on soft and hardwood for fine joinery. Only one cutter is necessary for producing 1/4" thick grooves, no longer two. 3 shims for adjustment after re-sharpening. You will need to lay two cutters upon each other for making 3/8" grooves. Long-lasting performance.