Hex Head Cap Screw Head Type Hex Diameter 1/4 In. Grade 8 Material Medium Carbon Steel Finish Yellow Zinc Plated Thread Size 1/4-28 Thread Type Fine Length under Head 2-1/2 In. Thread Length 3/4 In. Head Height 5/32 In. Head Width 7/16 In. Thread Style Partially Threaded Thread Direction Right Hand Proof Load 120 000 psi Tensile Strength 150 000 psi Rockwell Hardness C33 to C39 Meets/Exceeds SAE J429 ASME B18.2.1 ASTM F1941 FeZn5C Refills Mfr No 00081-2426-452