Well after looking at all the options have got a "Y" sized bottle from BOC, the other options were just to troublesome, £61 a year is pretty good I think.
Y size is a good size, but the re-fill charges with BOC are expensive as I have found out. But BOC is the only supplier I can find in Ayrshire and I am not prepared to drive all the way to Glasgow as the distance I have to drive would wipe out any savings I would make.
