The Broncolor Powerbox 900 Battery Power Supply is a lead cell battery which works as an inverter to power most AC (mains operating) Broncolor and Visatec monolights. (See Compatibility spec for exceptions). The Powerbox is for mono heads with their own power source. Pack heads cannot be plugged directly into it. Up to 3 heads can be connected to the Powerbox for a total of 900W/s. With a single 300W/s head, up to 240 full power flashes are possible. The unit comes with a charger that displays 3 status levels; red (empty), yellow (quick charge), green (trickle charge). Full charge from empty is approximately 2.5 hours. LEDs on the pack indicate Low Battery (red) or Ready (green). Although you can charge this version of the Powerbox from a 110 - 240V source, it outputs 120V only and should only be used with multi-voltage or 120V heads.