ProMag Industries

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. Features : - 50-Round Drum Magazine - Fits Smith & Wesson SD40 .40 S&W Pistol - Magazine Body Constructed of a Proprietary Dupont Zytel Based Polymer - Hybrid Steel Upper Magazine Tower - Injection Molded Magazine Follower - Magazine Spring Formed From Heat Treated Stainless Steel - Made in the U.S.A.