fair points,but its just a tank with some hosepipe coming off it!! I bought the pumpbox (cannot remember where from) so not really much to know about/learn,wired pumpbox to battery,hoses here there and everywhere for tank/pump.I have used an idea that came from this site as an external port,I just got a length of hose with a female hozelock type fitting on each end and put it through a ready made hole just under rear door of van(just removed rubber grommit) This 1 pipe can just be clicked onto my pump box for working ,and then clicked onto my tank for filling,dead easy and dead simple to make/install.The van can be kept shut and locked,the pipe is slightly squashed by the door,but not much.It seems to work just as well.Thanks to whoever posted this idea the other day.