Rugged steel cabinet with corrosion-resistant undercoating - standard colour is factory white, polar white and black available as options. Removable front panel on cabinet provides easy access and allows unit to be mounted at ceiling height. Solid-state pulse-type charger - current-limited, temperature-compensated, short-circuit proof and reverse-polarity protected. Unit comes standard with electronic lockout and brownout circuits. Sealed dust-proof transfer relay, test switch and LED indicator lights. Long-life, maintenance-free lead acid battery.