Using this rear fog light is straightforward. When you drive your 2015 - 2021 Subaru WRX or STI, the parking light will give extra light, especially in foggy weather. When you step on the brake, the F1 function may blink first for 3 seconds and then stay solid until you release the brake. When you put the car in reverse, the reverse light will come on, helping you see better and making others around your vehicle more aware. To install, first lay out all the hardware and the plug - and - play harness. Install the lamp and find a good route for the wiring so that water won't get into your car. Then plug in the harness and test all the functions. Remember, you can turn the F1 blinking on or off according to your preference. As for maintenance, just keep the lamp clean. You can use a soft cloth and mild cleaner to wipe it. Check the wiring harness periodically to make sure there are no loose connections or signs of damage.