Available in a number of capacities, ranging from 5 rounds to 40 rounds, this Roller Follower Magazine designed for use in today's popular AR-15 rifles is built with a special feature that aids in feeding and reliable operation. In place of a traditional follower, the magazine features an anti-tilt roller follower, which means that rounds will be kept level for feeding, reducing the chance of a misfeed. Each AR-15 Roller Follower magazine is designed for use with the 5.56 NATO cartridge, and the magazine body is constructed using DuPont's proprietary Zytel polymer, which has been proven to be durable and long-lasting. Constant spring pressure is provided by a heat-treated chr Mfg: Pro Mag