The MILWAUKEE® 1/2" Drive 27MM Metric 6-Point Standard Socket with FOUR FLAT™ Sides was designed from the ground up to be part of the most versatile socket family. The 1/2” drive sockets feature an innovative design with four parallel flat sides, which deter rolling and are wrench-compatible. The metric socket sizes are stamped into the flats providing improved, easy-to-read visibility. This standard socket has been optimized geometry to reduce bolt rounding and stripping. Milwaukee backs their 1/2” Drive Metric Sockets with a lifetime guarantee.