Spiral router bits are made by Amana Tool, the leading manufacturers of high quality wood cutting tools. Amana Tool 46423 SC Spiral Plunge 3/8 D x 1-1/4 CH x 1/2 SHK x 3 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: 3/8; (B) Cutting Height: 1-1/2; (d) Shank: 3/8; Overall Length (L): 4; Flutes: 2.