Cut perfectly fitted tongue-and-groove joints on stock between 1/2" And 3/4" Thick with a table-mounted router and this assembly. The tool consists of an arbor with an integral shank, two identical, removable slotting Cutters, and a pair of bearings. To cut tongues, sandwich one bearing between the two cutters (as in drawing a). to cut slots, mount one cutter between the two bearings (as in drawing B). Each set contains two complete Tongue & Groove assemblies, one to cut tongues, one to cut slots, #55407, diameter (D): 1-7/8, cutting Height (B): 3/4, shank (d): 1/2, overall length (L): 3, B1: 1/4, T: 1/4, replacement bearing: 47708, Material Size: 1/2" Through 3/4" Thick, C: 1/2, Wings: 2, 55407 2-piece carbide Tipped Tongue & Groove 1/2 kerf x 1-7/8 dia x 3/4 x 1/2 inch Shank set for 1/2 - 3/4 material