Power Sentry batteries fit in the tightest of applications, including low-profile lensed troffers, downlighting and industrial lighting fixtures. They also feature an innovative Quick-Disconnect wiring harness that makes field maintenance and upgrades quick and easy. Specification grade emergency ballast to operate oneor two lamps (4' or shorter) or one8' lamp. Factory or field installed inside or outside (field only) fluorescent fixture to operate lamp(s) at reduced light output, providing optimum glare-free illumination for a minimum of 90 minutes upon interruption of normal power.