The world’s first production double-stack 12GA 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.