Best for achieving smooth finish on hard plastics.• cutting diameter: 1/4" • cutting height: 1" • shank diameter: 1/4" • overall length: 2-1/2" • flutes: 3 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.