Package: Includes 10 pcs of 3.7" LED Trailer Marker Lights 6LED, available in blue box and red; includes free screws and hole spacers. Hole spacers are used to adhere the back of the marker light or the surface to be installed for waterproofing. These tiny gap lights need to be connected to a 12v power supply. The wire cable is about 11 inches long and can be connected in series with the speaker wire to make it longer; LED lights can be used as marker lights, running lights, side marker lights, license plate lights, indicator lights, identification lights, interior lights, under-dash lights, sidewalk lights, golf cart lights, cockpit lights, step lights, deck lights, Trailer lights, led concierge lights, tail lights, stair lights, truck lights, etc. The LED strips are hardwired with 2 wires, black for negative and white for positive; these surface mount lights do not have an on/off switch and the wires come out from the back of the center, since each truck light comes with two wires , so they can only be used for one function at a time; Tips and Warranty: 1. These lights are not dimmable; 2. These lights cannot be set to strobe, of course, it can be achieved by connecting a toggle (on/off) switch; 3. When multiple lights are connected, they can be connected in parallel; 4. These trailers are polarity related, if the polarity is reversed, they will not work; 5. These are waterproof, not submersible. Please do not use it underwater.