Features: Brand new and high quality Easy to use: Pour a cup of hot coffee, place the Stirling engine on the cup and it will work magically. When it slows down, it means the coffee is at the right temperature to drink. It can also work on ice cubes. Some people place the Stirling engine on a glass of hot water and then put a few small ice cubes on top of the Stirling engine. This makes the temperature difference much larger than normal, and then it runs faster and more crazy. The engine model is made of high-quality metal and elegant craftsmanship, which makes it sturdy and durable. Through practical use, 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 uses, such as children's science projects, physics/mechanics learning, classroom demonstration props for teachers, friends, family members, parents, children's birthday gifts, etc. It can also be used as a creative decoration for the desktop. When a guest arrives, place it on a cup full of hot water and gently press the flywheel to make the flywheel spin very magically. All your guests will want to know what happened and the ice was successfully broken. Package includes: 1x Stirling Engine Model Specifications: Material: Metal Bottom Diameter: Approx. 9.8cm/3.85in Note: 1. Please allow 1-2cm error due to manual measurement, please make sure you do not mind before ordering. 2. Due to the difference between different monitors, the picture may not reflect the actual color of the item.