Tool Steel Flat Stock, Steel Material, Width 3/4 in, Thickness 5/8 in, Fractional Size 5/8 in x 3/4 in x 18 in, Finish Unfinished, Length 18 in, Length Tolerance +0.125 to +0.250 in, Hardness Scale 200 to 235 BHN; Rockwell B94 to 99, Grade A2, Standards ASTM-A681, FED-QQ-T-570, SAE-J-437