The Exposure Support Cell 8.7A is an additional add-on power supply in a robust carbon fibre shell. Simply connect to any light through the Smart Port to extend burntime or combine with the Boost Cable to charge USB (Universal Serial Bus) devices (some Apple products are incompatible). Supplied with a mounting block & a 80cm cable they can be easily mounted or stashed in a pocket. They are recharged using the standard Exposure Lights charger, not supplied.