Hello Dave, I have no experience of the Gaslow or the Litew8's mentioned by Peter T. However before you purchase such bottles, do check that your local gas supplier will be prepared to refill the specific cylinders you purchase. As the owner of the bottle the onus is on you to have the bottles regularly checked for safety, and to be able to provide the filler with appropriate certificates of test if they ask. The filling company are obliged to satisfy themselfs that the the container offered is fit for purpose before they refil. They may refuse to fill if they cannot verify the containers suitability.