If you want one of the older ones, the III is the one to get, because it can take a modern strobe system. The II I think may be able to use electronic strobe with modification, but it is definitely not TTL. The II was made in the days of flash bulbs (yes, there were underwater flashes that used flash bulbs). I don't think the III is TTL flash either, but it can sync with the Nikonos flash units using the stock connectors. NOT that I recommend flooding a Nikonos III, but if it does flood, if you deal with it in a timely fashion, you can probably salvage the camera. Flood a V and it will be toast for sure.