1/2"-20 x 2-1/2" ASTM A574 Hex Drive Black Oxide Finish Alloy Steel Socket Cap Screw / THREAD CLASS: 3A THREAD DIRECTION: RIGHT-HAND THREAD LENGTH: 1.500 INCHES MINIMUM FASTENER LENGTH: 2.440 INCHES MINIMUM AND 2.500 INCHES MAXIMUM HEAD STYLE: C49 FLAT CHAMFER HEAD DIAMETER: 0.735 INCHES MINIMUM AND 0.750 INCHES MAXIMUM HEAD HEIGHT: 0.492 INCHES MINIMUM AND 0.500 INCHES MAXIMUM INTERNAL DRIVE STYLE: D5 HEXAGON NOMINAL THREAD DIAMETER: 0.500 INCHES WIDTH ACROSS FLATS: 0.375 INCHES MINIMUM AND 0.379 INCHES MAXIMUM THREAD QUANTITY PER INCH: 20 MINIMUM TENSILE STRENGTH: 170000 POUNDS PER SQUARE INCH HARDNESS RATING: 38.0 ROCKWELL C MINIMUM OVERALL AND 45.0 ROCKWELL C MAXIMUM MINIMUM YIELD STRENGTH: 150000 POUNDS PER SQUARE INCH MATERIAL: STEEL OVERALL SURFACE TREATMENT: CADMIUM OVERALL AND CHROMATE SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TY 2 CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL THREAD SERIES DESIGNATOR: UNRF SPECIFICATION/STANDARD DATA: 80205-NAS1351 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD