This 3 piece set allows double-sided traditional rail & stile joinery with either doweled or mortise and tenon joints. Interchangeable center cutter and bearings (included) for 1/4" or 1/2" panels. Interior doors typically use 1-1/4" stock with 1/4" edge panels and exterior doors use 1-3/4" stock with 1/2" edge panels. Included cope cutter for tenon joints allows any length of tenon for extra-strong joints.  Carbide tipped.