The X-15 design is the most compact and versatile 50 round magazine ever produced for the AR-15 in 5.56×45/.223 and most 300 AAC Blackout. Designed and built of the highest grade materials to give it unparalleled function, and rigidity. Engineered using our proven coil magazine technology, which allows side by side staging of ammo in a single stack. The streamlined design allows for no separation of ammunition during function, preventing malfunctions and lending to it’s compact design. Our patent pending tension relief device allows the X-15 to operate nearly unlimited spring loads, allowing it to operate in weapons with capabilities 1100 rounds per minute. The profile is shorter than a standard 30 round magazine and 3 inches shorter than a surefire quad stack magazine. User friendly ergonomics and the ability to use your sling makes this the choice magazine for 3 gun competitors. Coated in Cerakote for friction reduction and proven reliability without using lubrication, and given a lifetime warranty. Manufactured in the USA, fits most M16/AR-15 rifles with improved M4 feed ramps. May require fitting in SCAR 16, Bushmaster ACR, and Robinson Arms XCR. Will not workin IMI Tavor. No tools necessary to load or operate.