Ok well shipping was fast of course. I purchased the 13L for my section hike of the AT. Wanted something that will hold all my clothes other than what I will be wearing and the size I believe is perfect. Puffy jacket, change of underwear, Socks, another outfit, base layer and anything extra that will need to stay dry. I filled it and ran it under the sink for a few mins and everything was dry so I don’t have any doubts what u put in will stay dry so that concern is no longer. I wouldn’t submerge it but under normal use it should be fine. I also sprayed the seams inside and out with waterproofing for just an extra layer of protection, which it probably didn’t need it. As for the build quality, it’s perfect. Typical Sea to Summit, good quality. It seems thin and it is but it also seems that for what I’m intending to do with it it should last many seasons unless I snag it on something. Not to fear it is of good quality. Buckles are nicely made and fit together very good and can be replaced if in time that becomes necessary. This bag weighs next to nothing so for Ultra lighters it’s great. My suggestion is that if u wanna use it for clothing to stay dry for hiking it’s perfect. If u wanna use it for a food bag, I would recommend using Dyneema instead. Unless u are not worried about animals and such. This dry bag will not hold up to mice, critters, bears etc. But to keep the contents dry this bag is a no brainer. Dry, light weight and build quality it’s the one to get. Just pick the size u need. Hope this helps. I’m happy with mine and u will be too, just use it for what it is intended for. As long as u don’t submerge it it will be completely water repellent I’ve tested it.