Niagara Cutter N55808 Carbide Square Nose End Mill, Inch, TiAlN Finish, Roughing and Finishing Cut, 30 Degree Helix, 4 Flutes, 4" Overall Length, 0.250" Cutting Diameter, 0.250" Shank Diameter Four flutes produce a better finish than fewer flutes Square nose end mills (also called square end) create sharp, unrounded cuts Titanium aluminum nitride (TiAlN) coating lubricates the end mill for high-temperature stability and abrasion resistance at high cutting speeds, offering better heat resistance than TiN and TiCN coatings Carbide can run at higher speeds than high-speed steel, resisting abrasion and high cutting temperatures Center-cutting design allows the end mill to plunge into material like a drill bit while also performing conventional surface milling