It never ceases to amaze me, how many people do not analyze their own cylinders (a lot of it, plain laziness). I even had a buddy who was Adv. Trimix trained who did not analyze his Nitrox stage bottle. Of any divers out there, he should have been the first to analyze & should know the importance of it. He just said,... "I'll just go off your analysis". I was flabbergasted. After some discussion, he decided to check his cylinders. Good thing,.... one had a higher concentration than he expected. I carry my own analyzer & analyze my own cylinders,... every time. I basically trust no one with my life, but me. It just isn't worth the risk to me.