Armstrong 18-620 1/4-Inch Drive 6 Point Impact Socket, 5/8-Inch Made in the USA - quality and availability Radius corner design engages the flats of the fastener, not the corners, providing up to 15-Percent -20-Percent more torque while reducing fastener rounding, enhancing the turning of worn fasteners EYE-D markings optimize size visibility, also providing SAE / metric differentiation 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