Milwaukee 1/2 in. Drive 21MM Metric 6-Point Socket with FOUR FLAT Sides

Milwaukee Sockets were designed from the ground up to be part of the most versatile socket family in the industry. The innovative socket design has four parallel flat sides, which deter rolling and are wrench-compatible. Socket sizes are stamped into the flats for improved easy-to-read visibility. Optimized socket geometry helps reduce bolt rounding and stripping.