Tool Steel Flat Stock, Steel Material, Width 4 in, Thickness 3/8 in, Fractional Size 3/8 in x 4 in x 36 in, Finish Unfinished, Length 36 in, Length Tolerance +0.250 to +0.500 in, Hardness Scale 220 to 255 BHN; Rockwell B97 to 102, Grade D2, Standards ASTM-A681, FED-QQ-T-570, SAE-J-437