Features: brand new and high quality Similar to the working principle of internal combustion engines: Burning alcohol lamps provide power heating to expand the internal gas, thereby increasing the power of the internal molecular gas to act on the flywheel. With the help of the flywheel, thermal energy will be converted into mechanical work. It has a wide range of application, perfect for kids' science project, physical/mechanical learning, teache's demo props on the class, gift for friends, families, kids, etc. The product has been assembled and can be used directly. Superior metal structure, rugged and durable to use. An for ideal choice as a gift for friends, kids, family and more. Through hands-on operation, you can observe the entire process of Stirling engine operation, more intuitive understanding of Stirling principles, and deepen your interest in physics. Made of high‑quality metal material, hard, corrosion‑resistant, and long service life. Specifications: Material: Metal Size：16cm/ 6.3 in Package Includes: 1 x Mini Stirling Engine Model 1 x Alcohol lamp (without alcohol) note: Please allow 1-3cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item.