This SAE Recommeded Practice provides test procedures, requirements, and guidelines for high-mounted stop lamps and high-mounted turn signal lamps intended for use on vehicles 2032 mm or more in overall width. This document applies to trucks, motor coaches, van type trailers, and other vehicles with permanent structure greater than 2800 mm high. This document does not apply to school buses, truck tractors, pole trailers, flat-bed trailers, pick-up truck with dual wheels and trailer converter dollies. The purpose of the high-mounted stop lamp(s) and high-mounted turn signal lamp(s) is to provide a signal over intervening vehicles to the driver of following vehicles.