1/2" Cutting Diameter,5/16" cutting length. CMT Mortising Bits are designed specifically to rout perfect mortises with no splintered edges or rough bottoms. The negative (downward) shear angle of the cutting edges pushes the wood fibers down as they cut, eliminating the frayed edges you may have experienced with older bits. Constructed with thick micrograin carbide tips, these bits are great for both natural wood and wood composites. Our bits are available in sizes to fit most popular mortising jigs.