Radius corner design engages the flats of the fastener, not the corners, providing up to 15% -20% more torque while reducing fastener rounding, enhancing the turning of worn fasteners. EYE-D™ markings optimize size visibility, also providing sae / metric differentiation. Unique socket retention method, cold form ball recess, provides consistent secure retention of the socket to the drive tool eliminating the possibility of either a loose fit or tight fit. Socket wall dimensions are optimized to provide strength while retaining access to restricted fasteners. Manufactured from high alloy steel using the most up-to-date manufacturing process and heat treat for greater strength and durability.