I bought some of these to keep some things safe, and I must say they are extremely good quality and have kept my things perfectly safe. I have not stress tested them, I don't know what they are like if they fell in water for example. But mine have lasted me months and worked amazingly well made from a very high quality plastic. I seriously love these bags and bought several packs of both sizes and I would strongly recommend owning some they are extremely handy for all kinds of things... Just some advice is please just make sure you double check it is fully sealed, run your fingers down the seal a few times and you will feel a bump if there is a gap and not closed properly. You need to start right from the corner and work your way down, do NOT start sealing half way down and then come back and do the other half.