ProMag Industries Magazine, Drum, 40 S&W, 50 Rounds, Fits Smith & Wesson SD40, Polymer Construction, Black DRM-A102 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.