It's a burst disk system. It uses three layer of foil tape. Air enters the blowgun into the system until it burst the foil tape. The fastest opening valve around so it needs very little air and will get most of the air behind the nerf before it exit the barrel. Makes it very light weight. Total weight is 5.5lbs. The only con is reloading of the burst disk can take a while. But you do have two barrels to shoot before you need to reload it. I'm able to fire one at a time or both at the same time. I've created burst disk inserts that makes it faster to reload. Takes me about 5-10 seconds to reset the burst disk for both. It uses cam lock coupling to make the change of the burst disk faster.