Installed in Office Buildings, Factories, Hospitals, Schools, Shopping Centers, Casinos, Airports, Train and Bus Terminals. Listed to UL 924 by ETL. Pure Sine Wave Output preferred for LED Lighting Loads. Automatic monthly and annual self testing. Compact 24" wide x 17" high x 9.5" deep, space-saving enclosure with front access. Double Conversion, "no-break" online system for all applications and lamp types.