This 15-rd magazine is for the Ruger P-series pistols in 9mm. It is constructed from heat-treated blued- steel, with a follower, lock-plate, and base-plate molded from a proprietary DuPont Zytel based black polymer; and using a spring wound from Chrome-silicon wire and heat-treated for strength and reliability.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