This sale is for a very rare Mamiya 7 External Battery Case to fit the Mamiya 7 and 7ii cameras. It is in mint condition – it has probably never been used at all. The instruction sheet can of course be downloaded from this website.
This case is designed exclusively for the Mamiya 7/7ii cameras for use in cold weather. It allows you to keep the battery inside warm clothing where your body temperature can maintain the battery voltage. It takes the same 6v battery as used in the camera.