Interesting- I had no idea that the US had different standards for SCUBA tanks as compared to Europe. That explains why I've never seen one with the higher pressure rating.

I wonder how it is that we came to standardize on the higher pressure for our paintball gear in the absence of an equivalent local standard for SCUBA? I have seen many paintballers use SCUBA tanks to refill their own marker tanks in the field, but always at only 3,000 PSI. To fill to 4,500 PSI, most of the better paintball fields have a communal air compressor (often brought out on loan from a local paintball supply store for the weekend) which players can use for a small fee.