Fangrui Product Details Fans Have Excellent Craftsmanship, Made Of Metal. The Hotter, The Faster You Go! A Stirling Engine Is A Heat Engine That Operates Through The Cyclic Compression And Expansion Of Air Or Other Gases (working Fluids) At Different Temperatures, Thereby Converting Thermal Energy Into Mechanical Work. The Engine Principle Is Intuitive, Educational Toys And Teaching Experiment Equipment Can Effectively Cultivate Childrens Interest In Learning, And Can Also Be Used In Classroom Teaching, Which Is More Intuitive And Easy To Understand. A Great Gift For Friends Or Family, Or On Your Desk Or Anywhere! Size:16x8.5x7.5cm Material:metal Colour:gold Package Contents: 1 X Stirling Engine Motor Model Only The Above Package Content, Other Products Are Not Included. Note: Light Shooting And Different Displays May Cause The Color Of The Item In The Picture A Little Different From The Real Thing. The Measurement Allowed Error Is +/- 1-3cm.