T-Bolt, High Strength, 4140 Steel, Black Oxide Finish, Thread Size 5/8-11, Thread Type UNC, Length under Head 4 In, Thread Length 2 In, Head Height 13/32 In, Head Width 1-1/8 In, Slot Size (In) 5/8 In, Tensile Strength 15, 820 PSI, Rockwell Hardness C32-C36, Meets/Exceeds Grade 5