all of the three are from the early 1960's and still working! The depth gauge had that time already a little problem: when you went below 80, it did not show the actual depth correctly (if you have a look at the inner circle on the scale, you can imagine why ...). But the watch still rules o.k.! And if you belong to the hard-core divers, there is no problem using the USN table!
Bottom Line is: when all the electronic stuff fails, use these old-fashioned things AND your brain, too!