This magazine is for Ruger Mini-14. The magazine body constructed of heat treated steel with a black oxide finish for durability and harsh use in the field. A chrome-silicon wire spring and precision molded polymer follower ensure reliable feeding and function.ProMag magazines are designed utilizing traditional stamping and welding of heat-treated high carbon steel. Every ProMag magazine is backed by a lifetime guarantee against manufacturer's defects. Features: Magazine body constructed of heat treated carbon steel with black oxide finish Injection molded magazine follower Magazine spring formed from heat treated chrome silicone wire Made in USA