T-Bolt, Medium Strength, Steel, Black Oxide Finish, Thread Size 1/2-13, Thread Type UNC, Length under Head 4 In, Thread Length 2 In, Head Height 5/16 In, Head Width 7/8 In, Slot Size (In) 1/2 In, Tensile Strength 8514 PSI, Rockwell Hardness C25-C34, Meets/Exceeds Grade 5 T-BoltsMedium carbon steel with black oxide finish.