I bought this for some additional storage on our tandem prior to a tour in the USA. It's velcro straps can be a bit fiddly to get tight and to take off, but hold it securely with no catching on the legs. We had little rain to prove it's waterproofness, but as it seems completely airtight I don't think there would be any chance of water ingress. It needs careful packing as it can be awkward finding smaller items amongst others through the opening, but it kept surprising me how much would disappear into it. After nearly 3 weeks of touring it has come back looking as good as new.