The .350 Legend DURAMAG SS™ is an AR-15 pattern magazine designed for serious shooters who require the most out of their magazines. With the Duramag SS .350 mag you are getting .350 specific rib geometry which is crucial to reliable feeding and round stack internally. These magazines are also marked with .350 on the body and the follower to help with quick identification. Constructed from premium 410 Stainless Steel and built with advanced interior and exterior geometries to ensure ultimate reliability and feeding. These magazines utilize the T-360™ coating to ensure incredible performance and product longevity through the harshest conditions. The .350 Legend magazines are available in 5rd, 10rd and 20rd capacities and safe for extended storage while loaded. DURAMAG™ will not flex or swell like polymer due to storing while loaded or environmental / temperature changes.