Hi Dave, my buddy Captain Craig De Wit uses the Apollo version of the 1st stage/pillar valve for his needled MCCR Drager Ray and Dolphin. He's the owner/operator of the Papua New Guinea liveaboard MV Golden Dawn, and so of course being out in the middle of nowhere, he services his own gear. I'm assuming he took apart one of them and O2 cleaned it, so it must be possible. He put them on 2 1ltr aly cylinders and stuffs the O2 in one side weight pocket of the Dolphin BC and the dil in the other side and uses the butt mount nitrox cylinder for BO. It's a very clever and compact rig for rec CCR diving and the cheapest rig I've seen, if one were to start with a used Drager. Not sure how he mounts the little cylinders on the Ray, haven't seen that rig yet. I'm sure if you email him he can give you details... -Andy