Grand General's standard LED (light emitting diodes) lights offer an inexpensive way to upgrade your vehicle lighting. LEDs are brighter and have lower amperage draw making it possible to add more lighting without upgrading your charging system. This 4" round LED light is ideal for heavy and medium duty trucks. The light contains 40 diodes and is used for stop/turn/tail function. The light is conveniently easy to install and just requires a standard 3-prong pigtail (not included). The quality of the lights makes them a great choice for your tail light needs, Grand General's quality safety LED lights are built to meet or exceed DOT (Department of Transportation) and/or SAE standards.