The G&G SGR 556 AEG, which sports the newest gearbox tech from G&G, is said to have the all the features in an AEG according to RedWolf Airsoft TV (RWTV) in  this video review... "G&G Armament has come out with their long awaited SGR 556 AEG, featuring their highly advanced G3 split gearbox which features a whole host of customizable functions as well as an empty magazine cutoff compatible with standard M4 AEG magazines, the SGR 556 promises to be the ultimate evolution of the decades old M4 AEG platform and Andrew checks it out in this exclusive review."