Features: Made from high-quality materials and designed for lasting performance. Easy to operate,compact and portable,making your experience more wonderful.Easy to carry to everywhere you want to go. A stirling engine is a heat engine that operated by cyclic compression and expansion of air or other gas (the working fluid) at different temperatures, so that there is a net conversion of heat energy It has a wide range of application as, perfect gift for kids to improve children's eyes and curiosity, Physical/mechanical learning, teacher’s Demo props on the class, birthday gift for friends, fami It's really interesting and imaginative toy. Art design,gift packaging design,low price,strong power,exquisite workmanship,safer. Specifications: Material: Metal Color: As picture shown Szie: Approx. 16x8cm/6.69x3.14in Weight: Approx.498g Package Includes: 1 Set Sterling Engine Model note: 1.Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!