This solid carbide flush trim router bit set includes one up Cut spiral flush trim Bit and one down Cut spiral flush trim Bit. They are designed to provide precise, efficient cuts and offers extreme durability. The spiral design effectively reduces chipping. For use with soft & hard woods, ply-woods, composites, laminates, plastics and some non-ferrous metals. The two independent ball bearings with forced on steel collars at the tip of each bit ensures smooth worry free use. 1/4″ shanks.