Our take: The A&K manufactured 5,000rd M4/M16 super high capacity box magazine is one of the BEST high-volume mags you can get for your M4 / M16 / AR AEG. It effectively turns your AEG into an effective support weapon, without any major modifications needed on the actual receiver of your rifle. A large loading compartment opens to allow you to pour up to 5,000 BBs into the mag, and a large, easy to turn gear wheel located at the bottom of the drum mag allows you to effortlessly wind BBs up the feed and into your AEG for seamless full-auto firing. Compatibility: This box mag is compatible with A&K, DBoys, CYMA, JG, Echo 1, ICS, G&G, Classic Army and Tokyo Marui M4/M16 AEGs. Excellent quality and finish. NOTE: The gun shown in the product images is NOT included.