YM455B Powered by solar power with a solar panel on the back， no battery needed. When exposed to sunlight， the spider will start its mini engine and shake itself as if looking for food， very funny. An excellent teaching aid to provide students with some basic knowledge about solar energy. Great gift for kids. Package Details Weight: 24.61 g Size: 13*10.3*2 cm Package Includes 1 × Mini Funny Solar Powered Shaking Spider Robot