I went today to exchange a 3.9kg orange propane cylinder for a new Calorlite 6kg cylinder so that I had two full ones fora month long trip away. It seems that since 01 Aug Calor has changed the policy so that you now have to buy the Calorlite and take outa new ownership agreement. Instead of £18 which my first one cost me the new price would have been £29. Since I have managed for years with only two 3.9kgs I decided to not buy the new Calorlite. So if you are thinking of changing get out there now as there may be some suppliers who will do a simple exchange.