NUPROL - STANAG 370rnd Hi-Cap Magazine - Black is a STANAG Type magazine which is designed to fit any Airsoft 6mm BB Gun which accepts this style of magazine, such as M4, L85, 416 and more. The magazine is constructed with a Realistic Alloy Outer Shell, with durable Polymer Internals. The magazine is of a Hi-Cap (High Capacity) design, which means that it will hold more BB's than other Mid-Cap magazines at the cost of being wound up. The magazine is wound using the bottom winding wheel, which feeds BB's up the feed tube to the weapon. The magazine holds up to 370 rounds, and is filled from the top using a large filling window. The magazine is first filled with BBs, then wound from the bottom until a louder audible click is heard, once the magazine has been wound additional BB's can be loaded in the top, filling the remaining space. This type of magazine is perfect for regular Airsoft Skirmishers as the magazine holds lots of rounds, and increases the length of time between having to stop and reload, allowing you to put more rounds down range without stopping.