Carbide tipped. Raised panel bits with back cutters are designed for making raised panels from 3/4 stock. Produces panels that are flush with the door frame and have a full 1-1/2" reveal. Tongue thickness is adjustable from 7/32" to 1/4" for compatibility with most stile and rail cutters. The back cutter profile is square and can be changed to a radius using the optional model No. 54-562 back cutter. 1/2" shank.