An extended magazine for Smith & Wesson M&P pistols chambered in 9mm. Made by ProMag. 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 made in the USA and backed by a lifetime guarantee against manufacturer's defects. Magazine springs are precision wound using heat-treated chrome silicon wire and each and every step of the assembly process is checked and double checked in order to maintain the same consistent level of quality.