Description: Material: made of glass, purely handmade a high borosilicate glass craftwork Automatic rotating: It will rotate automatically under the sunlight or strong irradiation. Wide application: fun science gift desk ornament. It can be used for decoration, decoration, teaching, simple and generous shape, developing creativity. Educational: Made of glass with an internal vacuum. Through the light can be turned by itself, through the cold wind can also be turned in the opposite direction, a magical science exploration teaching instruments. Principle: When the light black fan absorbs heat energy, white fan releases heat energy, it can promote the four fans rotation. Size Chart: Height:13cm/5.12inch Ball diameter:7.5cm/2.95inch base diameter:6.5cm/2.56inch Package Includes: 1 windmill Note: 1.This is not infant toy, please take away from children to avoid eating. 2.Please allow slightly errors due to manual measurement and different monitors.