They automatically light up to create a disk like light over your tyre rims when your tyre spins, just put the batteries and shake it to see the lighting effects
Safety: the led lights have super bright, energy saving and long lifespan led can increases night time and bad weather visibility for safety
Waterproof - the valve has a light mouth small waterproof case it lights up itself using high-quality metal gold-plated, inner zone button batteries
Other features: no battery connection required - no need to connect to the vehicle battery
Easy installation: simply screw it onto the tyre valve, twist off your original valve cap, and replace with this valve cap led light