A standard magazine can hold from 10 to 30 BBs. However high-capacity magazines, which are also known as Hi-cap, can hold about 100 to 600 rounds BBs. These magazine usually have a wheel at the bottom to draw BBs up into the "ready" tube by rotating manually. BBs in the ready tube will be drawn into the gun when fired. Usually a Hi-cap will make more noise when you move around because the BBs inside will bounce around and the user will need to spin the wheel occasionally to ensure enough BBs are drawn up to be fired. Standard magazines are apparently hold much less BBs, that you may need 2 or 3 of them during a game, but they make no noise. For the cost or airsoft players who do not like reloading, the hi-cap magazines are definitely a better choice.