- Drum housing constructed of a proprietary DuPont Zytel based polymer
- Magazine upper tower has full length steel internal insert stamped and welded like the factory magazine
- Injection molded magazine follower
- Magazine spring formed from heat treated stainless steel
- Made in USA
ProMag magazines are designed utilizing both traditional stamping and welding of heat-treated high carbon steel, and modern precision injection molding of mil-spec polymer compounds. Every ProMag magazine is backed by a lifetime guarantee against manufacturer's defects. Made in USA.