Screw these led light tubes into the air valves on your bike tires and let the show begin! Each tube automatically turns on a light show at dusk while riding. The ten colorful led lights automatically turn on at dusk, channeling through a streaming sequence of blinking while the wheels turn to illuminate your bike. Set of two. Each light measures 3-3/4" long. Requires 3 button batteries each, included. Recommended for ages 13+.