When it is dark, they automatically light up creating a disk like light that appears to hover above your wheels, bring more color to your car/bike, bring more enjoyment to your drive. Safety during night driving. More energy-efficient with light and motion sensors. LED flash light safety light with built-in motion sensor. Rust resistant and auto shining, 100 percent waterproof. Durable and high impact. No battery connection required - no need to connect to the vehicle battery as it has an inbuild battery. Waterproof - The valve has a light mouth small waterproof case. It lights up itself using high-quality metal gold-plated, inner zone button batteries. Easy to install: Simply screw it onto the tyre valve. Twist off your original valve cap and replace with this valve cap LED light.