PERPETUAL MOTION DESK TOY Adult science toy, mini steam engine kit is not only a highly playable educational desktop toy, it also has a wide range of applications as a science project for children, for physics/mechanical learning, or as a classroom demonstration for teachers. It also makes a great gift idea. Children under 12 years old should be supervised by their parents during assembly. For more information about the Stirling engine, please refer to Wikipedia. Specification Material. Stainless steel and aluminum Net weight: 500g Package size: 7.08 x 2.75 x 2.75 inches Package contains Engine x1 USB air compressor x1 Tool bag x1 Detailed manual x1