A container designed as a refillable cylinder used to hold compressed medical grade sulphur hexafluoride (SF6) under safe conditions at high pressure. It is typically filled with SF6 when delivered from the gas/device supplier and includes a valve stem, an opening/closing valve, and will be graded according to size (capacity) and colour-coded to denote SF6 content. The cylinder is typically made of steel and must be used together with a pressure regulator in order to release the SF6 at the correct working pressure. SF6 is used predominately as a tamponade gas to aid the healing process from retinal surgery.