Spiral-flute bits combine a shearing action in cutting with an auguring action in chip clearance. The shearing action yields an especially clean accurate cut while the auguring action clears chips from the cut. The ‘down-cut' cuts from the surface down leaving a smooth edge at the surface. Special unique carbide grade increased clearance geometry and razor-sharp cutting edges with polished flutes provide a superior finish and longer tool life especially in abrasive materials. Great for production settings and excellent for creating grooves and dado cuts in particleboard, plywood and laminate. Primarily used on CNC machines and other automatic routers. Can be used with handheld and table-mounted portable routers, #46422, direction down-cut, (D) diameter 5/16, (b) Cutting height 1, (D) shank 5/16, overall length (L) 2-1/2, flutes 2, 46422 Solid Carbide spiral plunge 5/16 dia x 1 inch x 5/16 shank down-cut