The Mackwell Advanze-2 ST516 is a 5 pole isolating relay emergency inverter for use with T5, High Output and Circular high efficiency tubes between 22 and 55w. It has a 3 hour duration and should be used with a 6 cell battery pack. These inverters have several features including: Switch Mode Power Supply for thermal overload protection and Cathode heating ensures safe and reliable starting of T5 lamps in a variety of conditions and uses.