This double-stack ProMag Smith & Wesson M & P-40 Magazine is constructed from heat-treated, blued steel. It is equipped with a follower, lock-plate, and base-plate molded from a proprietary DuPont Zytel-based black polymer for smooth loading. The magazine utilizes a spring wound from Chrome-silicon wire and heat-treated for strength and reliability. This double-stack ProMag Smith & Wesson M & P-40 Magazine is compatible with the Smith & Wesson M & P series of pistols in .40 S & W. Made in the USA. Note: Shipping restrictions are active in AK, CA, CO, CT, HI, IL, MA, MD, NJ, and NY for magazines with 16 or more rounds.