Ditto that Paul much better than BOC....
both do "rent free" gas... It is something like £45 "right of use" for 3 years,
You would say that wouldn't you
Those here who have spoken with me will have heard something like..."There is a three year right of use charge, a refundable deposit and you simply pay as you go for the gas"
Why not stick to plain English and simply use the word 'rent' because that's what it is. Are you hoping the customers might think it's something else by using the strange term "three years right of use". It's fog.
http://www.plainenglish.co.uk/
You could add that the bottle remains your property and customers pay you money up front, in advance, over a three year period to rent it. And if they ask if you have any rent-free schemes, and/or can the customer buy the bottle or use their own, then the answer is a resolute 'No'.