When you put the radiometer in the sun, the vanes keep . It is a gift, send it to our friends or family.They love it! The stronger the light, the faster it turns. If possible, place it on a window sill or other place with strong light. It is made of glass,so it is fragile. It is suitable for children over 13 years of age. Put it in the office or the living room is very beautiful., Weight: 0.25683853523 pounds, Manufacturer: Tuesoa