X Products X-15 AR 15 High Capacity Magazine is one of the most compact and versatile 50 round magazines ever made for the AR-15 in 5.56x45/.223 and 300 AAC Blackout full length. It is designed and built from aluminum and steel and uses minimal plastics in the operating assembly. This gives this mag unparalleled function and rigidity. Engineered using proven coil magazine technology which allows side by side staging of ammunition in a single stack. The stream line design allows for no separation of ammo during function and prevents malfunctions. The patent pending tension relief allows the X-15 to operate nearly unlimited spring loads, allowing it to operate in weapons with 1100 round per minute capabilities. The X-15 magazine is shorter than the standard 30 round magazine and 4 to 5 inches shorter than a surefire quad stack. User friendly. No tools necessary to load or operate.