Amana - A57329 12mm Cut Diameter Upcut Router BitThese Amana bits will produce clean, smooth cut edges in acrylic and other plastic materials. Cut Diameter: 12mm Shank: 12mm Cut Length: 38mm Overall Length: 76mm Flute Type: O Flute Upcut No. of Flutes: 1 No. of Flutes: 1 The bits are made according to strict tolerances from an exclusive high quality carbide grade and polished to a mirror finish using Amana's unique process. The upward spiral geometry will eject chips up out of the cut where they can