The one the crew had for this job was about 18" long.Allen key, to disassemble -- and it often took some doing . . .
They also filled the cylinders in place on the boat between dives, and on some trips it was a very wet trip out and back and no covers on the valves [that did not have a regulator on them], most regulators were taken off ready for the next fill before the trip back, now the DIN one is a big gaping hole without the insert, how many times has this happened?
I am stating the obvious for most people reading this post when I say "do you see a problem?"