4 lamp SPW provides 13 percent energy savings and 6 percent greater light output compared to a standard 4 lamp T8 electronic troffer. 20 percent longer lamp life (24,000 hours vs. 20,000) provides longer relamping intervals for lower maintenance costs. Payback of additional cost (compared to standard 4 lamp troffer) is less than one year in most cases. Shipped with factory installed high lumen output/high color rendering T8 lamps. UL listed, suitable for damp locations.