This is a very rare accessory – an underwater housing for the Leningrad rangefinder cameras.
It is made of aluminum alloy and painted in bright red and yellow. The housing is a professional-grade device, solid, well designed and well made. There are several attachments that are mounted on the camera body and lens. They engage with the control levers.
The housing is very clean and complete. I am not sure about the condition of the seals, but they are serviceable parts.