Finally, I arrived after a long search to the Russian oxygen rebreather IDA-57. From the 1960s up to the end of the GDR the "KSK 18" used the combat swimmer of the GDR this unit as diving device. My unit bears the KSK count number 45 and has been obviously used in some "war-mission" :-). I tried therefore to restore the device in diveable condition, but largely in original condition. The device is worn in front of the chest and is attached by the neck strap and the waist belt.
I show here some pictures of restoration, problem solving and many details and drawings of the most important building parts.