The model gas engine model CO2 is a piston engine that will be compressed with carbonic acid. The gas tank of the engine is filled with carbon dioxide cartridges that are normally used for the home siphon. The parts are not in their original box, but they appear to be unused with no known damages. The directions are in German. The items are secured in a zip lock bag. The instructions are in good condition with no known wear or tears. The packaging measures approx. 8" x 8"