Controlled by the exclusive mobile phone app, no need to be programmed by computers. Download a variety of pictures, GIFs or upload your own pictures, and DIY your own texts, pictures and GIFs to display on your bicycle wheel as you want. The app will monitor your riding speed, maximum speed and record your journey time and mileage, etc.. IP55 Waterproof epoxy coated LED design, no need to worry about rainy days' riding and damages caused by normal bicycle washing. Powered up by a built-in 1300mAh rechargeable lithium battery. Applying scope: The wheel diameter of 26 inches and above (The outside diameter of the hub must be less than 38mm). Special U design and the customized clamp respectively fit perfectly for bike hubs and bike spokes.