Your choice of M4 magazines of different load capacities at Laylax right now. The Garuda M16/M4 <130/300/900 Magazine Series can fit most AEG rifles including the Krytac Trident Series. The 300 and 900 magazines have the usual wind-up need to push BBs up the magazine to be fed. The 900 version can be good for an AR AEG that you want to use as a support weapon.