Description: 【Thermal Energy Driven Fan】: This DIY Solar Powered Windmill Model operates without battery, automatically rotating when heated. It provides a captivating and straightforward demonstration of the heat insulation effect of solar films, making it an eye catching and easy to use tool 【Compatibility】: Designed to be used with a solar film testing lamp, this Solar Powered Windmill effectively showcases the thermal penetration and insulation properties of different film materials, offering more intuitive understanding 【Visual Solar Film Testing Tool】: The fan's rotation speed visibly changes before and after applying the solar film, allowing customers to easily comprehend the product's heat insulation performance. It's an ideal tool for in store demonstrations 【Educational Science Model】: Ideal for physics classes, science education, and energy knowledge teaching, this Desktop Wind Mill Model allows students to experience the fascinating process of thermal energy conversion firsthand 【Eco Friendly Design】: With its mechanical operations requiring no power source or battery, this structure is suitable for children to operate and display. Additionally, its compact and charming design makes it a fun desktop ornament that adds creativity to any office space Specification:10cmx7cmx18cm/3.94inchx2.76inchx7.09inch Package Includes: 1 DIY Solar Powered Windmill Model (Need Assemble) Note: 1.This is not infant toy , please take away from children to avoid eating. 2.Please allow slightly errors 1-2cm/0.39-0.79inch differences due to manual measurement.