Blue Temper Spring Steel 0.016 In Thick x 1.50 Inch Width x 900 Inch Length Thickness Tolerance ±0.001″ Width tolerance is ±0.010″. Length tolerance is ±1/2″. C1095 Blue Tempered and Polished Spring Steel. Rockwell hardness C 48-51. MIL-S-7947, AISI-1095, SAE- 1095, and AMS-5122.