Tool Steel Flat Stock, Steel Material, Width 4 in, Thickness 1/8 in, Fractional Size 1/8 in x 4 in x 18 in, Finish Unfinished, Length 18 in, Length Tolerance +0.125 to +0.250 in, Hardness Scale 188 to 223 BHN; Rockwell B90 to 97, Grade S7, Standards ASTM-A681, FED-QQ-T-570, SAE-J-437