Description: Mini Size Single-Cylinder LED Stirling engine physical motor heat power generator external combustion engine model kit. Theory: Similar to internal combustion engine: the burning alcohol lamp provides heat power to make the expansion of gas inside, then the gas molecular internal power increasing and working strongly to the flywheel With the help of the flywheels, heat energy will convert into mechanical work Great educational toy, classroom or laboratory experimental teaching aids, cultivate children's interests in physics, more intuitive and easy to understand Great gift for your friends or families. A stirling engine is a heat engine that operated by cyclic compression and expansion of air or other gas (the working fluid) at different temperatures, such that there will be a net conversion of heat energy to mechanical work. Specification: Material: Metal+Glass Generating Voltage: Approc 3-5V Fuel: 95% alcohol (alcohol is not included) Size Chart: L x W x H: Approx 8.3 x 9 x 14cm/3.27 x 3.54 x 5.51inch Package Includes: 1 Stirling Engine Model Note: The alcohol is not included