We just got a new van which has an internal water pump so the thing you stick in the aqua roll is just a pipe with a filter on one end and the connector to the van on the other. The shroud on it is too small to cover the inlet at the top of the aquaroll so we have to use one of those elasticated jar top things to keep creepy crawlies out.
Les - if you've got a Go Outdoors near you, they're doing the 40 litre Aquaroll for £39 just now. You need a discount card - £4 if you don't yet have one or you could order online (sorry, don't know what the postage would be..).
------------- Best Wishes and Happy Travels,
Feecamp