Armstrong 36-210 1/4-Inch Drive 12 Point Deep Aerospace Socket, 5/16-Inch Made in the USA - quality and availability Meets applicable aerospace standards 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 Thinner socket wall dimensions provide increased access to restricted fasteners with no loss in socket strength Bolt clearance holes have larger diameters and depths to accommodate a wider variety of fasteners