Works Surprisingly Perfect!
I got one of these and was a little iffy about the "ziplock" type closure so I did some testing. I put a tissue into the bag and dunked it in the sink. Tissue did not get wet. Took it to the bottom of a 5' swimming pool, pushed it together and played with it and it did not get wet. Took a smart phone through the Subway slot canyon in Zion NP (very wet canyon) and IT DID NOT GET WET!!! The Small is perfect for your smartphone and is touch sensitive so you can use your touchscreen phone through the bag! I wouldn't recommend using these for your cameras as I have tried other bags for that in the past and they all suck. Just get a waterproof camera. You can find them relatively cheap and they work great! Get one of these for your smart phones to protect them from water and sand! Easy too open, easy too close.