It is pretty well documented that the flippack tent fabric is sturdy but not very water repellant. As a soon to be owner of one I have been looking around for products that will help in this regard. Nikwax seems to be a favorite and TACODOC has kindly written up about this product. I am somewhat familiar with 303 products because I have inflatable boats which specifically recommend 303 aerospace protectant (not the fabric guard). They make a fabric guard product also which is recommended by the manufacturer of Sunbrella. With that kind of recommendation I was thinking of using it on my flippac tent. Has anyone used it for this application? Here is one review of this product http://www.myboatstore.com/scotchguard.asp but I have seen some other test done several years ago that rated 303 higher than Nikwax