I have 'aquired' (Just a bit of skip diving) 4 pairs of thick silicon o rings from work ideal for holding down the back of shower caps when the soft top is on. They are light blue and take no time to fit and better than zip-ties / ty-wraps IMHO.
TTFN
Rich
If anyone wants some drop me a line!
Got a load of big black ones (Ooo er!) too