Spiral router bits are made by Amana Tool, the leading manufacturers of high quality wood cutting tools. Amana Tool 46476 Solid Carbide Double Flute Down-Cut Ball Nose Spiral 1/8 R x 1/4 D x 1 CH x 1/4 SHK x 2-1/2 Inch Long Router Bit leaves an excellent finish and expels chips quickly. Used for carving, decorative doors and sign manufacturing. Excellent for: Aluminum, MDF, Sign Foam, Soft/Hard Plastic, Soft/Hard Wood. SPECIFICATIONS: Direction: Down-Cut; (D) Diameter: 1/4; (R) Radius: 1/8; (B) Cutting Height: 1; (d) Shank: 1/4; Overall Length (L): 2-1/2; Flutes: 2.