Music Wire - Per ASTM-A228 or AMS 5112. Music wire springs are not recommended for applications where the temperature exceeds 121 deg. C (250 deg F.) Stainless Steel Type 302 - ASTM-A313 or AMS 5688 spring tempered (chemical & physical only). Stainless steel springs are not recommened for applications where the temperature exceeds 260 deg. C (500 deg. F).