I have bought both as I plan to tackle resealing most, if not all, of the awning and other rails on the caravan at the weekend. The nearside rail definitely needs doing as does one along the back of the van as both are letting in water very badly. I was originally doing to use Caraseal as it's locally available and very cheap but then in the caravan shop saw rolls of mastic which look alot easier to work with. Which is preferable? And do they need time to dry or cure? How long will this take? I am hoping it will be dry on Saturday and then I can cover the caravan over once complete just in case it rains.