Tool Steel Flat Stock, Steel Material, Width 6 in, Thickness 1/4 in, Fractional Size 1/4 in x 6 in x 36 in, Finish Unfinished, Length 36 in, Length Tolerance +0.250 to +0.500 in, Hardness Scale 177 to 212 BHN; Rockwell B88 to 95, Grade O1, Standards ASTM-A681, FED-QQ-T-570, SAE-J-437