Bike Wheel Light with 20 led beads & red flash lights provides cool lighting effects; Fits most bicycles with wheel circumference less than 78 3/4' With sensor, it automatically switches on at night when bike stays moving & switches off when environment brightens or you're stationary for 1 minute It provides eye-catching lighting to make you visible to road users Wrap to create special lighting effect or cut to fit your bike Powered by 2 AA batteries (Not Included), you can use it everywhere you go