Rip Cutting Tools 5/16" 3-Flute SE Carbide End Mill, ZRN Coating for Aluminum, USA 273-0312Z, Specs: Cutter Diamter: 5/16, Shank Diamter: 5/16, Length of cut: 13/16, Overall Length: 2.50, Number Flutes: 3, Base Material: Carbide, Coating: ZrN. These tools feature a 45 Degree Helix, Variable Indexed Flutes, High Rake for Effective Cutting on the Newest CNC Machines as well as lower RPM Manual Machines and ZrN Coating, the premier coating for Aluminum and other softer materials. Made in the USA