By jove I think he's got it!From the look of this it is exactly the same as mine, that being an old style A-clamp, and the bottle is probably rated at 232bar.
The difference between the old and the new style is that on the new A-clamp the a-clamp bit screws out and becomes a din fitting. Old style ones are A-clamp only. (Is that right Mr Allen?).
Tom Allen should be able to sell you an A-clamp fill rig, on the presumption that you want to fill your paintball air system from this dive tank.