ProMag Industries Magazine, 40 S&W, 25 Rounds, Fits S&W M&P-40, Steel, Blued Finish SMI-A13 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.