ProMag magazines are made in the USA and backed by a lifetime guarantee against manufacturers 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 :21-Round MagazineFits Sig Sauer P320 9MM PistolMagazine Body Constructed of Heat Treated Steel with Black Oxide FinishFlat Dark Earth EndplateInjection Molded Magazine FollowerMagazine Spring Formed From Heat Treated Chrome Silicone WireMade in the U.S.A.