Features: brand new and high quality The operation is simple: pour a cup of hot coffee, put Stirling on the cup, and it will work magically. When it slows down, it means that the coffee temperature is suitable for drinking. It can also work on ice cubes. Some people put Stirling on a glass of hot water, and then put some small ice cubes on the top of Stirling. This makes the temperature difference much larger than normal, and then it runs faster and crazier. The engine model is made of high-quality metal and elegant craftsmanship, which is sturdy and durable. Through hands-on operation, you can observe the whole process of the Stirling engine, understand the working principle of the Stirling engine more intuitively, and deepen students' interest in physics. It has a wide range of applications, such as children's science projects, physics/mechanical learning, classroom demonstration props for teachers, friends, family members, parents, children's birthday gifts, etc. It can also be used as a for creative decoration for the desk. When a guest arrives, place it on a cup full of hot water and gently push the flywheel to make the flywheel turn very magical. All your guests want to know what happened and the ice broke successfully. Specifications: Material: Metal Bottom Diameter: Approx. 9.8cm/3.85inch Package Includes: 1x Stirling Engine Motor Model note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item.