Try dave at split screen-look on spares page
http://cgi.ebay.co.uk/Porsche-911-912-wheels-Fuch-Fuchs-PAIR-911-912-VW_W0QQitemZ270208144110QQihZ017QQcategoryZ27385QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
I got this one a couple of years ago for my van 8)
Had a look inside ...not horse hair....coconut fibre
You just put water in it
Only used it once last season, went to Dubs in the Park, must have looked a real prat as it was p***ing down