Best for achieving smooth finish on Hard plastics. cutting diameter: 3/16″ cutting Height: 3/4″ shank diameter: 1/4″ overall length: 2″ flutes: 2 low helix bits perform a more lateral movement with less upward or downward motion resulting in a smoother finish on single layer materials. These bits are a better choice for hard Plastics such as acrylic and phenolic. Down Cut End mills Shear in a downward direction causing the uppermost layer of the material to be pressed down against the material just below it. This motion leaves a perfectly clean top surface edge. A concentration of wood chips in the work path will occur. Hose away excess wood chips to prevent bit breakage.