Cool! Not something I have seen before! It seems like they made a lot of specialist webbing towards the end of the war. Does his basic pouch have a QR fastener or a regular snap?
WPGG .... I have no idea. It looks like the loops that hold the canisters themselves may be elastic. I have never seen one of these in person. It looks horribly unbalanced ... perhaps this was done for the photographer or because of the gas cape it's sitting on ?