The typical types of steel tanks in terms of pressure are:
200 bar = 2 900.75475 pounds per square inch
232 bar = 3 364.87552 pounds per square inch
300 bar = 4 351.13213 pounds per square inch
The 200bar tanks are older type and can be filled as the 232bar ones.
Volumes are a bit more tricky to convert, since we use litres instead of cu ft and don't want to even try to do the math here.
The 300bar tanks are usually used as single tanks, 232bar tanks are used in twinsets.
We also have aluminium tanks but they are mostly used as deco/stage and small argon tanks.
.Janne
ps. Oh, yeah, you need a DIN-connector in your reg to use a 300bar tank, yoke can't take it.