Open End Wrench, Alloy Steel, Black Oxide, Head Size 5/16 in, 3/8 in, Overall Length 5 1/4 in/ OVERALL LENGTH: 5.125 INCHES NOMINAL LARGE END HEAD THICKNESS: 0.188 INCHES NOMINAL SMALL END HEAD THICKNESS: 0.188 INCHES NOMINAL WRENCHING SURFACE SIZE: 0.313 INCHES NOMINAL FIRST END WRENCHING SURFACE SIZE: 0.375 INCHES NOMINAL SECOND END WRENCHING SURFACE SHAPE: OVAL BOTH ENDS INTERNAL SMALL END HEAD ANGLE: 15.0 DEGREES NOMINAL LARGE END HEAD ANGLE: 15.0 DEGREES NOMINAL MATERIAL: STEEL OVERALL SURFACE TREATMENT: OXIDE OVERALL STYLE DESIGNATOR: 104 DOUBLE HEAD