Partsam Submersible 4 Inch Round Red LED Trailer Tail Light w/Reflector Stop Tail Turn 10 Diodes, 4" Round LED Trailer Stop Tail Turn Running Light with Reflex Flange for Boat Trailer RV TruckS Round trailer tail light serves 3 functions when properly mounted: Stop light, Tail light, Turn signal light; inner diameter: 110mm(about 4-1/3"); outer diameter: 139mm(about 5-1/2"); sealed, waterproof; corrosion resistant; flange mount with built-in reflex reflector; 10 red LEDs; red lens This 4" LED Tail Light is Great for Jeep TJ CJ YJ or RV Motorhomes Trailers Trucks, also you can use it on tractors, semi-trailer, dump truck, bus, boat, camper, cargo, special vehicle and Heavy trucks such as Peterbilt Kenworth Freightliner Volvo etc. Built-in reflex reflector removes the need for a separate reflector; 12V Sealed light Assembly, 10 Diodes , flange mount, waterproof lens. EASY TO INSTALL: Black Wire - Ground; Red Wire - high brightness; White Wire - low brightness. Offering customer technical service, feel free contact us for technical, installation and use question.