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. Features : 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 MAGAZINE CAPACITY NOTICE This magazine exceeds 10 rounds of capacity and may be restricted or prohibited in CA, CO, CT, DC, HI, IL, MA, MD, NJ, NM, NY, RI, VA, VT, WA, and select municipalities. It is the buyer's responsibility to verify local, state, and federal laws before purchase. Orders that cannot ship to a restricted address will be canceled and refunded.