Lights minimize freight damage while expediting loading and unloading operations. Provides uniform visibility inside trailers or around dock areas. All Dock Loading Lights are UL listed. High Pressure Sodium, Double Arm, Adjustable Lights in series LLS offers much higher lumens/watt output and a very long lamp life. Its illumination color rendition (yellowish) is not as desirable as an incandescent. It typically requires several minutes to turn on and even longer if in a cold environment. Low operating cost. Units are supplied with a 50 watt bulb.