DOUBLE PROTECTION:The fluorescent car tire valve caps features illuminated plastic inserts and clear housing protection to prevent valve stem corrosion. Our tire valves caps inside with the Rubber Sealscreate a tighter, more effective seal, so theres no air leaking on long, tough drives. FLUORESCENT EFFECT:The inner layer of the valve stem cover is designed with luminous material, which can make the car decorated with Tire Valve Stem Caps lights at night. When your wheel starts to move, it automatically flashes and creates a circle of light that makes your car/motorcycle/bike look beautiful. NOTE:Since the fluorescent material needs to absorb the light source, it glows at night. Stem cpas do not absorb light sources when stored in airtight packaging for extended periods of time. Illuminate with LEDs or place them in sunlight for 5-15 seconds before using fluorescent stem cpas for the first time. EASY INSTALLATION:Easy installation without tools. Simply screw it onto the tire valve stem. It's easy to install or remove when you want to check air pressure. WIDELY USED:The inner diameter of tire valve caps is 8mm, fits most cars, buses, SUV, trucks, motorcycles, and bicycles, etc, keeping the tires of vehicles at the proper inflating level.