CMT 529.381.31 Plug Cutter, 1-1/2-Inch Minor Diameter, 1-31/32-Inch Diameter, 5/8-Inch Shank 4 Cutting Edges, 6-5/16-Inch Overall Length. Max suggested RPM: 300 on hardwood, 500 on softwood. Made of alloyed steel, long-lasting cutting performance. For making plugs in soft and hardwood.