robert, i assume that you have changed calor 3.9's (or 4 as its printed on the bottle) for calor 7's in which case you just have to be aware that it is a left hand thread, but if you have changed from any other manufacturer eg camping gaz or you have changed from butane to propane or vise versa then you will also need to source the corect regulater. even if your van is fairly new and has the new fixed regulater you would need to buy the correct pipe with the corect fitting for your gas bottles, its fairly confusing at first as every manufacturer seems to use theire own type of fitting. we used to use butane in summer and propane in winter but we got so fed up in the end with changing regulaters that we just use propane all year now. we have found we use about 1 1/2 bottles of gas a year with about 85 nights in the van so even if we go abroad two full bottles is more than enough.