Initially I had these fitted when I had the camper attached. Since I have gone over to the AHA , they only really get used for leveling the car when camping
This tank gets pressurised by the ARB pump in the engine bay and is on a pressure switch , which is quite handy as it means I always have air immediately available.
The pressure in the bags can be adjusted with this in-cab controller pictured below
The bags can also be inflated manually with the 2 connectors (red and black pipes seen here) .
The coupling on the right is for my tyre inflation hose , which also uses the reservoir , so pumping up tyres is pretty quick compared to just using a compressor