The tail light lens is a crucial part of the tail light assembly. Tail lights are external lights, contained in either a metal or plastic housing, that are fixed to either side of the car at the rear. The tail light lens is a protective covering, made from plastic or glass, which fits over and forms the outer surface of the tail light.

The primary function of the tail light lens is to protect the bulbs that make up the tail light. The bulbs in the tail light assembly are fragile and can get damaged if exposed to the weather, which can cause the bulbs to fail.

The tail light lens ensures that the tail light is completely protected from the elements and also offers protection to the bulbs from minor knocks and scrapes.  The tail light lens also helps to reduce the glare produced from the tail lights, which helps motorists travelling behind. 

If the tail light lens is broken, smashed, cracked or is damaged in some other way and not fitting securely over the bulbs in the tail light assembly, you run the risk of broken or short-circuited tail light bulbs. It's important, therefore, to replace the appropriate tail light lens when damaged to avoid damage to the bulbs. Replacing a broken tail light lens with a tail light lens will ensure you get a part that fits securely to your car's tail light assembly.