How it Works: A Stirling engine is a heat engine that operates by cyclic compression and expansion of air or other gas (the working fluid) at different temperatures, such that there is a net conversion of heat energy to mechanical work. A Great Explanation: Teacher can make the explaining process much straightforward and students can better understand principle. Safe Opeartion: Run freely on the top of a cup of hot water, no need to fire a alcohol lamp, for children. Operating Requirement: Start temperature difference between the product bottom contact and circumstance should be 25. Easy to Use: Gently flip the wheel, then it can run itself. Considerate Design: Exquisite frosted plunger can avoid leakage and the reduce abrasion. Note:If the friction between flywheel and support is big, use a little graphite dry lube quiet it down nicely. 't use oil, because it will lead to oil-dirt. Low Temperature Stirling Engine Model DIY Kit Principle of Operation: Heating Expansion / Cold Compression Speed: 180rpm (max.) Note: Children under 12-year-old should be accompanied by adult when playing this product. color:Silver+gold Material:Metal Package Contents: 1 x Low Temperature Stirling Engine Model DIY Kit 1 x Chinese and English instruction manual Only the above package content, other products are not included. Note: Light reflection 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.