The Phase One FireWire 800 DC Plug Kit is designed to provide continuous power to the IQ1, IQ2, and IQ3 digital backs. With this plug installed and powered from a standard Phase One battery charger power supply, it is now possible to connect the computer to the IQ digital back via USB, and have power coming in through the FireWire connection at the same time - thus not having to change the battery in the digital back from time to time. If you are also using the XF Camera System with an IQ3 digital back, the XF camera body will also be charged due to the PowerShare feature.