Crowfoot Socket Wrench, Alloy Steel, Chrome, 1/2 in Drive Size, 38 mm Head Size/ OVERALL LENGTH: 3.438 INCHES NOMINAL WRENCHING SURFACE SIZE: 38.0 MILLIMETERS NOMINAL SINGLE END DRIVE SURFACE SIZE: 0.500 INCHES NOMINAL SINGLE END WRENCHING SURFACE SHAPE: OVAL SINGLE END INTERNAL DRIVE END SHAPE: SQUARE SINGLE END INTERNAL MATERIAL: STEEL OVERALL SURFACE TREATMENT: CHROMIUM OVERALL STYLE DESIGNATOR: 53 OPEN END SPECIFICATION/STANDARD DATA: 05047-ASME B107.100 CAT 21 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD NONDEFINITIVE SPEC/STD DATA: 2 TYPE AND 2 CLASS