CFF cylinders have an aluminum core with silica (glass) fiber wrap and are DOT-E11005-3000 rated. These are high-pressure oxygen cylinders for service pressures up to 3,000 psi (207bar).(3 year Hydro interval) They can be optionally ordered with a DIN-477 (Euro-norm) valve with gauge. Servicable in the USA to 2200 psi @ 14CF.