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 Principle:When the light black fan absorbs heat energy,white fan releases heat energy,it can promote the four fans rotation