Hi, I am looking to buy a pressurised CO2 system soon and want to get a 3 or 5Kg CO2 cylinder so I can supply my tank with CO2 for months without worrying about re-pressurising my tank. However I know there must be alot of regulations around pressurised gas and want to make sure I buy a CO2 bottle that is legally refillable. Whether its a fire extinguisher or a normal pressurised cylinder I dont mind. Also is it easy to find a company that are willing to re-pressurise my gas cylinder for me? Thanks in advance guys!