This top bearing slot cutter router bit routes a 1/4" x 1/4" slot. The overall diameter is 1-1/4" and 1/4" shank. Top bearing slot cutting router bits are specifically designed for on-site deck board slotting to be used in conjunction with hidden deck board fasteners. The bearing's position allows for easy slotting on deck boards that are already positioned on the deck beams. There is no protrusion at the end of the bit that will interfere with any underlying wood.