Spiral router bits are made by Amana Tool, the leading manufacturers of high quality wood cutting tools. Amana Tool 46225 SC Spiral Plunge 1/8 D x 13/16 CH x 1/4 SHK x 2-1/2 Inch Long 2 Flute 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: 1/8; (B) Cutting Height: 13/16; (d) Shank: 1/4; Overall Length (L): 2-1/2; Flutes: 2.