NUPROL - STANAG 30/140rnd Adjustable Mid-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 looking Alloy Case, with durable Polymer Internals. The magazine is of a mid-cap design and loaded from the top, meaning the BBs are released on a spring system, meaning no rattle or winding once the magazines are full preventing you from being heard during a Skirmish. This magazine is unique in the fact that the capacity can be switched between 30 and 140 rounds, making it great for Airsoft Skirmishers who also attend Mil-Sim games by quickly switching to the lower capacity. This magazine is the perfect purchase for any Airsoft Skirmisher due to its low price and high quality, with the added bonus that should you one day visit a low-cap only site it can be quickly changed to suit your needs.