Power your camera continually, and without interruption, with the ONsite Relay Camera Power System from Tether Tools. Equipped with a built-in 7.4V, 1,200mAh lithium battery and a 5 VDC input via USB, this system will provide power, while being connected to an external power source for a nearly constant source. When connected to a 2A USB battery pack or an AC adapter, the ONsite Relay can still be able to provide a constant supply of power to your camera, and thanks to the internal battery the system will support hot swapping of external power sources. An LED indicator light will shift from green to yellow to red to show battery percentage so that you will not accidentally lose power during a long time lapse or video production. This system is compatible with numerous camera systems through the use of a separately available coupler. This coupler fits into the battery compartment of your camera and acts as a dummy battery to supply power.