I received this set of 3 little dry bags as a birthday present. At first I was a little disappointed by how small they are because I had only used big dry bags before, but after a while, I found them to be extremely useful.
All the bags are made of lightweight nylon that is coated on the inside with waterproofing. They have the fold over top with a plastic clip. The small blue bag is the perfect size for phone, wallet, and keys (have to keep that key fob dry!). I use the large green bag for other small items I want to get to quickly and easily. I keep the medium grey bag around to loan to friends who show up with their phone in a ziploc bag.
The clip on top of each bag makes it easy attach to a line or my clothing. In fact, the little blue bag has become so useful that I carry it around with me in daily life, like a lady would a purse. These bags don't hold air for very long which made me nervous that they might let water in, but so far everything inside has stayed dry.