Features: brand new and high quality Working principle: Similar to an internal combustion engine, the burning alcohol lamp provides power and heating to expand the internal gas, thereby increasing the power of the internal molecular gas on the flywheel. The engine model is made of high-quality stainless steel 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. The Stirling engine model has been assembled and can be used directly. Specifications: Material: Metal Size: Approx. 16x7x8cm/6.29x2.75x3.14 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.