The mackwell ast514 is an autotest low profile emergency inverter with 5 pole isolating relays for use with t5 high efficiency tubes between 14 and 28w it has a 3 hour duration and should be used with a 5 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