Amana Tool 55421 1-5/8 Diameter by 11/16-Inch Cuttting Height by 1/2-Inch Shank Concave Stile Rail Router Bit Set, 2-Piece For 3/4-Inch material Carbide Tipped, Industrial Quality 1-5/8 Diameter, 11/16 Cutting Height, 1/2-Inch Shank 2 Wing. Concave profile. For use only in a table mounted router.