Freud"s exclusive Micrograin carbide insert knives are thick enough to be resharpenable for the ultimate in cost savings and are inexpensive enough to be considered disposable. Use with the RP1000 or RP2000 insert cutter head. Raised panel knives produce a 1/4-inch thick tongue in 5/8-inch stock and can be used with the optional RP-OPS or RP-OPB back cutter to make a 1/4-inch tongue in 3/4-inch stock. Covered by Freud"s limited lifetime warranty.Covered by Freud"s limited lifetime warranty