3/4 in hub|Constructional feature dust/corrosion-resistant|Fiberglass reinforced polyester body and push to test switch, continuous silicone cover gasket, nickel plated brass hub, stainless steel cover screws, aluminum lampheads|The electronics consist of a solid state charger, transfer circuit and low voltage battery disconnect circuit|Capacity is sufficient for the connection of 6 output watts|System supports 4 light heads in any main/remote combination utilizing up to 6 Watts of output power|This allows for a main unit without any light heads to drive up to 4 remote units or any other combination of 4 lights|Remote lamp head assemblies (one or two) are available for mounting of lampheads away from main power supply system|Provides 100% lumen output for 90 minutes of operation with four light heads or 180 minutes of operation with two light heads|The solid state charger maintains maintece-free NiCd battery at full charge, upon power failure or utility voltage (AC) below 50 V, the DC emergency lighting load is connected to the battery|During emergency operation, the battery is automatically protected from deep discharge damage by a low voltage battery disconnect (LVD) circuit, upon restoration of normal power, the charger brings the battery to full capacity within acceptable UL time standards