Fog light, just as its name implies, is a light used on fog day and located below the headlight assembly. Fog lamps are usually mounted reasonably low—typically about 12 to 30 inches above the road surface—and angled downward to illuminate the ground below the fog.
Unlike headlights, fog lamps are not necessary. It is an auxiliary light. So when you buy a new car, your dealer will give you the option to have the fog lamp as an add-on.
Usually, the original fog lamp is halogen or LED light. Its power and lumen are very low. Now you can choose a bi-xenon or bi-led projector lens fog light to update your fog light. Royalin fog lens has a high beam and low beam. It can be used with royalin headlight lens together. So you can get 4 low beams and 4 high beams.


Fog light lens as a supplementary light and it can be used with a headlight in low visibility settings. Because of the poor lighting and the irradiation angle is low, the fog lamp can not be used as your driving lights.
While there are no regulations for when you should use your fog lamps, it’s recommended that you only activate them during certain situations, like the ones listed below:
Fog is the same as the clouds on the groud. Because we installed the fog lens under the headlight so the lighting can able to hit the groud, rather thn going straight into the fog.
On the rainy day, you can not open your car’s headlight. Driving light high low beam in a higher position and it can produce glare when used in heavy rainy day.
This is terrible weather. We suggest you do not drive a car in sand duststorm weather, but if you are driving and met this please open your fog lamp and maneuver your vehicle to safety while you wait for the storm to pass.
Although royalin fog projector lens is a bi-xenon and bi-led projector lens. They can provide both high beam and low beam similar to a headlight projector lens. And royalin fog bi-led projector lens had wide light on the road, but we still not suggest you use the fog lens as a headlight even not used the headlight as a fog light because of the different position and irradiation angle.
You must say it is my car, my fog light, and we can turn on the fog lens as our requirements. For example, on a clear day at dusk, we want to open the fog light to see the clearness of the road. But is this really legal?
But it’s important to understand that there may be road rules covering the use of fog lights in your country. For example, there’s a law in Florida that disallows the use of fog lights and other auxiliary lights when other cars are on the road—except in foggy conditions. Meanwhile, in Oregon and a few other states, there is a law that prohibits the use of fog lights when you are within 500 feet of an oncoming vehicle or within 350 feet if you are behind another car. This is to avoid the possibility of blinding other drivers with the glare. There are also states that regulate the color of your fog lights. For instance, in Washington and Colorado, fog lights must be limited to white or amber—or any color in between, in the case of the latter state. Always check your state or city laws about fog light usage to avoid any violations and untoward incidents.