The Indra Battery Pack from Phottix is designed to power the Indra 500 TTL light. It features dual power ports for working with two lights simultaneously and an LED display that provides feedback on the power remaining. A USB charging port makes it possible to use the pack to charge your mobile devices, and with optional cables it can also power up to two on-camera flashes or speedlights. The required Li-ion cells, sold separately, are easy to install and replace.