Putting a title on this is tricky because you can use them to keep things dry or you can use them to keep your wet things in. I used PUL fabric. I put (ish) in there because waterproof suggests that it will keep water in or out. It has a zipper so that isn't completely the case. It's great to put wet baby clothes or diapers in your diaper bag. It's great for throwing your wet swimsuit in. Take it to the beach and keep your stuff dry in your beach bag then use for your wet stuff when you head home. Small bags are perfect to carry cosmetics in your purse or overnight bag. They come in small, medium and large. Sizes aren't exact, but close. Sm 6"x9" is $4, med 9"x12" is $8, large 13"x13" is $10. Custom sizes also available.