This 5200 mAH battery pack provides an approximate 3-4 hours of extended battery life on the Sony A7R II & A7S II series cameras and is compatible with the Nauticam A7II housing. The battery pack fits just above the cameras electronic viewfinder and therefore cannot be used in combination with a hotshoe connection or Nauticam Flash Trigger for strobes. This makes the battery pack an ideal choice for dedicated video shooters.
For Sony A7 users with a Nauticam housing, the USB battery pack will not provide power while the camera is turned on. However the battery will charge the camera while the system is turned off. This allows the camera to be effectively charged from inside the housing while the camera is powered down in between dives.