Thanks to steady progress in the development of CO2models, these guns now bear little resemblance to those of the first generation. Whereas the early models were often simple and indefinite in character, one can now get authentic replicas that closely match the originals in appearance, handling and weight. Multi-shot replicas of this kind cannot be built if other power sources are used. Compact 12 g and 88 g CO2capsules now make it possible to build replicas of almost any kind of weapon. The liquefied CO2in the capsule enters an evaporation chamber where it turns into a gas and can pass a valve. Each time you pull the trigger, a certain amount of CO2is released, forcing a pellet out of the barrel. Users of Umarex and Walther CO2capsules can be sure that the seal between the valve and the CO2capsule will stay intact.