Made from medium carbon steel, Grade 8 cap screws have a greater tensile strength than Grade 5. Designed for use in high stress applications, these bolts shall be heat treated, oil quenched, and tempered at a minimum tempering temperature of 800 degrees (F). With thread extending 2 1/2" up the shaft, this bolt's Proof Load is 120,000 PSI with a minimum Yield Strength of 130,000 PSI and Tensile Strength of 150,000 PSI. HHCS1X312C8Y