Blue Temper Spring Steel  0.015 In Thick x 0.125 In Width x 300 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 50.
MIL-S-7947, AISI-1095,
SAE- 1095, and AMS-5122.