Tool Steel Flat Stock, Steel Material, Width 2 1/2 in, Thickness 1/2 in, Fractional Size 1/2 in x 2 1/2 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