14 years & up. Expand your knowledge of steam power with this self-assembly pneumatic engine model! This model shows how steam engine uses air pressure instead of steam to move and function. The use of a simple, inflated balloon is all it takes to get the gears set in motion. Approximate time to assemble: 2 hours. Measures 3.9"H x 3"W x 6.4"L. Includes 81 pieces.