Looking for a reliable way to double your magazine capacity, without coupling 2 magazines together? The ATI® Schmeisser® S60 AR-15 .223/5.56 60-Round Magazine is just what you need! Constructed of glass-reinforced polymer with a unique follower system, this patent-pending 60-round, double/triple-stack magazine is compatible with any standard AR-15 lower receiver (not included). Plus, this magazine features an upgraded, reliable bolt hold-open feature for enhanced performance.