sorry guys - just unpacked the pc after my move up to North wales
you want a reciever - part no L55AF
http://www.maplin.co.uk/Module.aspx?ModuleNo=4850&1&source=14&doy=8m6and a keyfob - part no L54AF
http://www.maplin.co.uk/Mproduct.asp?oc=L54AFi found it best to do a check on the web site of what store has what as some don't stock both items !!! together ,
so you may have a bit of running round , or wait for them to come up on the internet .
they work well on a trolly system , havn't put one in a van yet so can't comment on that .
I have set up 3 now and you can run 3 trollys working next to each other without turning each others water on/off ok
anymore info - fire away
john