Double-end cobalt square end mills have a nose on both their ends and can accomplish more milling tasks than single-end cobalt square end mills before they need to be replaced. When the cutting edges on one nose wear down, the end mill can be flipped over to expose the fresh cutting edges on the other nose. Cobalt end mills can be used at higher speeds and are harder and more wear-resistant than high-speed steel end mills. Sometimes called square-nose end mills, square end mills have a square nose and are rotated against a piece of stock to create a flat-bottomed groove with 90° inside corners in milling tasks. They are used for counterboring, side and face milling, and milling square shoulders.