We came across this at a caravan show on a very expensive motorhome and of course followed it up as it is something we have been trying to find for months. This is the greatest thing since sliced bread! The gas contents gauge is actually built into the cylinder itself and appears to be very accurate. We are up to refill number three and it has been correct every time. Some filling stations are even not charging us full whack when it is still a quarter full. So far we have only come across it fitted to the Australian made Manchester bottles. It is NOT an add on product - the valve has been modified to accept it.

Bob Eustace