Build your own models powered by air and water pressure to learn about the laws of physics. This unique kit allows you to build two different air-and-water-powered systems: water-jet propelled cars and hydro-pneumo (which simply means air pressure and water pressure) powered engines. The hydro-pneumo system uses a self-contained air-and-water turbine system as a motor. Construct 15 models including a truck, excavator, radar car, tank, antique car, helicopter, motorbike, backhoe, rocket car, forklift, roadster, propeller plane, grinder, and cutting machine. The water-jet propelled cars aare a fun outdoor activity, while the self-contained hydro-pneumo powered models are fun both indoors and out.