For users of the Tokyo Marui Gas Powered M870 Tactical Shotgun, they can check this Tonic Airsoft Reinforced Gas Tank made for it and available right now at eHobby Asia. This can shoot up to 80 shots when full and also increase initial muzzle velocity. Since it has a reinforced full metal housing, it is durable enough that it can take drops to the floor. It costs US$48.99 to order from the eHobby Asia online store.