ProMag Industries SMI 37 High Carbon Steel Magazine offers unmatched durability and performance, crafted from heat-treated high carbon steel for longevity. This USA-made magazine is built to survive the toughest conditions while ensuring reliable feeding with every shot. Engineered with a blend of traditional craftsmanship and modern technology, the SMI 37 combines traditional stamping and welding techniques with state-of-the-art polymer molding, resulting in a robust design that withstands rigorous use. Magazine body constructed of heat treated steel with black oxide finish Injection molded magazine follower Magazine spring formed from heat treated chrome silicon wire Made in USA Trust in ProMag's lifetime guarantee against manufacturer's defects for peace of mind.