Ok, it's late I no but I'm hooked on looking at wfp stuff for when I get on my toes.... I'm just wondering, how come some companies who make wfp systems they have like a big long tube on them, is that something to do with the reverse osmosis filter? Because it looks a lot longer than the usual RO filters I've been looking at. Question no.2 How come some companies who make the wfp systems use aswell as the RO system and the big long tube which I have no idea what it is....x2 di vessels? How come they use 2 of these and some companies have only 1 on there units?