The MILWAUKEE® 3/8" Drive 18mm Metric 6-Point Deep Socket with FOUR FLAT™ Sides was designed from the ground up to be part of the most versatile socket family. The 3/8" drive sockets are wrench-ready and feature an innovative design with four parallel flat sides to deter rolling. Metric socket sizes are stamped into the flats for better visibility. Optimized deep well socket geometry helps reduce bolt rounding and stripping.