DURAMAG Speed bodies are constructed of 6061-T6 aluminum and are type-III hard-coat anodized. Unlike other magazines that use inferior coatings to color their USGI style magazines Duramag's wide range of colors are part of the anodizing process and thus a part of the metal. These magazines and are safe for extended storage while loaded and will not flex or swell like polymer. With the Progressive die tooling Post and Hole design and fully robotic welding you can truly depend on these magazines to be consistent every time you buy them guaranteed.