These bits are specially designed to make glue joints for raised panels. Thanks to the interlocking "V" Joints, the mating surfaces are at an angle to the finished surface of the panel, not vertical, so the dark lines like those created by standard finger joint bits are not visible. Use to rout hardwood, softwood or composites in table-mounted routers. Bit does not have to be precisely centered in the work piece. Simply adjust the bit height 3/32" after routing the first piece, and then rout the mating piece.