Glow in Dark: These tire valves stem caps are made of Luminous Material. Give your car a unique luxury look, with beautiful dazzling. Excellent Air Tightness: Our tire valve caps have rubber seals inside, creating a tighter, more effective seal. This design to prevent air leakage can effectively improve driving safety. Material: Our tire valve stem cover features illuminated plastic inserts and clear housing protection to prevent valve stem corrosion. These valve caps can protect the valve, prevent water, dust, or sand into the tire; prevent the valve from leaking and ensure safe driving. Wide Application: The inner diameter of this tire air cap cover is 0.8mm, the outer diameter is 1.2mm, and the inner height is 1.6mm. Universal size fits more cars, bus trucks, SUVs, motorcycles, bikes,s or bicycles. Easy to Install: The package includes 4PCS green fluorescence valves stem caps, which can be easily tightened using your hand without any additional tools, very simple and convenient. Note: The product material is ABS leather + phosphor powder, which belongs to the storage light material. It absorbs light when there is light and emits light when it is dark. However, the exposure to the sun during production and transportation is short. If it does not emit light after purchase, please put the item in the sun. Scientific explanation: Photo-induced energy storage luminous powder is a fluorescent powder that stores light energy after being irradiated by natural light, fluorescent light, ultraviolet light, etc, and then slowly releases it in the form of fluorescence after the light irradiation is stopped. Therefore, at night or in the dark, one can still see the glow, lasting as long as several hours to ten hours