The Armstrong Tools 37-283 1/4" Drive 6 Point Metric Deep Socket 5.5mm is a high-quality socket that is made from durable materials and designed to provide years of reliable service. It features a radius corner design that engages the flats of the fastener, not the corners, providing 15%-20% more torque. This design also prevents rounding of fasteners and enhances the turning of worn, rounded fasterners -- extending fastener life and reducing chance of slippage.