Niagara Cutter N90223 High Speed Steel Square Nose End Mill, Weldon Shank, Uncoated (Bright) Finish, Finishing Cutting, 37-Degree, 2-Flute, 3.75" OAL, 0.688" Cut Diameter, 0.625" Shank Diameter 37-degree helix angle provides efficient cutting action and chip evacuation required to machine aluminum and other nonferrous materials Two flutes offer better chip-carrying capacity than end mills with more flutes High-speed steel is a common general-purpose steel for cutting tools Square end creates sharp, unrounded cuts Center-cutting design allows the end mill to plunge into material like a drill bit while also performing conventional surface milling