Union Butterfield 5110370 High Speed Steel (HSS) Square Nose End Mill, Inch, Double End, Weldon Shank, Uncoated (Bright) Finish, 30 Degree Helix, 2 Flutes, 3.5" Overall Length, 5/16" Cutting Diameter, 3/8" Shank Diameter High-speed steel tools are good for most general purpose applications, offering a combination of hardness and toughness for wear resistance Uncoated tools feature just the base substrate without any additional treatment or coatings and are suitable for a wide range of applications Weldon shanks feature a round shank with one of more flats machined into the side for easy indexing and alignment