Using this OLM rear brake and reverse light is easy. First, make sure your vehicle is a 2015 - 2021 Subaru WRX or STI (not compatible with Crosstrek without wiring modifications). Connect the plug - and - play harness to your tail light wiring before any other changes. Mount the lamp in the appropriate spot on your vehicle using the included mounting hardware. When you use the brakes, the brake light (which also serves as the parking light) will get bright. When you put your car in reverse, the reverse lights will blink for a few seconds and then go solid. If you want the reverse lights to blink continuously, follow the steps in the supplied instructions from your driver's seat. Remember, if you have a 13 - 17 Crosstrek, you'll need to modify the wiring by snipping, stripping, and tapping. To maintain it, just keep it clean with a mild car cleaner and a soft cloth. Check the wiring connections periodically to make sure they're secure.