590M Series Accessory Magazines pack more rounds into shorter magazines -- quickly and efficiently adding capacity. The world’s first production double-stack 12 GA shotgun magazine offers a shorter magazine length vs. capacity than competitor’s single-stack designs, providing better swing, balance and control. Magazine construction highlights: Hardened steel feed lips, over-molded steel shell ramps, easy-grip external molded design, proprietary self-lubricating polymer magazine body material, heavy-duty ASTM-A-228 music wire magazine spring, removable floor plate for easy cleaning, and a tough black oxide finish on steel components. For shooting flexibility, 590M magazines are available in 5, 10, 15, and 20-Round, and are for use with 2.75" shotshells.