I remember them, but have never used one..

That would be a little bit scary, depending upon PSI remaining and your depth and need to do multiple safety stops.. I think I've mostly used aluminum tanks, even tho they weigh a ton and I think they must be steel.. I own a tank, but have never had it serviced.. I'll dive in the pool with it, but wouldn't do open water until its been serviced.. luckily there's NOWHERE around here worth diving, so will never be an issue..

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Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..