Buyers Products 4 Inch Round Stop/Turn/Tail and Backup Light is used on trucks and trailers to meet FMVSS/CMVSS 108 regulations. The light is a convenient and efficient way to get a red stop/turn/tail and clear backup light in a single fixture. It uses a PL-3 connection for the stop/turn/tail light and a PL-2 for the backup. Lights are available in bulk (sold in multiples of 10) or individually in a kit that includes a grommet and plug for installation. They are backed with a limited lifetime warranty.