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 sold in quantities of 10 and backed with a limited lifetime warranty.