Fangrui Product Details Easy To Operate: Just Place It On A Cup Of Hot Water, And Gently Flip The Wheel Until The Wheel Can Run Automatically. Superior Performance: By Operating The Engine, Children Would Observe And Know The Operational Process And More Intuitive Understanding Of The Operating Principle Of Stirling Engine, Deepening Interest In Physics. A Classic Stirling Engine Model: Made Of Premium Metal, And The High Intensity Pc Material Is Heat- And Harmless. Transparent Body Gives You A Clear View On How Every Parts Work. Safe For Children: No Need To Fire An Alcohol Lamp, For Children. Fully Assembled, No Need To Install It Yourself. Great Educational Toy: Classroom Or Laboratory Experimental Teaching Aids, The Gift For Students, Teachers, Children, Friends And Colleagues. Net Weight:218g/7.7oz Colour:gold Material:metal+pc Size:9.9 X 11.4cm() Package Contents: 1 X Stirling Engine Model Only The Above Package Content, Other Products Are Not Included. Note: Light Reflection And Different Displays May Cause The Color