Spiral router bits are made by Amana Tool, the leading manufacturers of high quality wood cutting tools. Amana Tool 46331 Solid Carbide Spiral Plunge 3/16 D x 3/4 CH x 1/4 SHK x 2-1/2 Inch Long Down-Cut Router Bit combines a shearing action in cutting with an augering action in chip clearance. The shearing action yields an especially clean & accurate cut, while the augering action clears chips from the cut. The down-cut cuts from the surface down, leaving a smooth edge at the surface. SPECIFICATIONS: Direction: Down-Cut; (D) Diameter: 3/16; (B) Cutting Height: 3/4; (d) Shank: 1/4; Overall Length (L): 2-1/2; Flutes: 2.