These sandwich bags are mini versions of their wet bags. They have the cute fabric on the outside, a waterproof inner layer and a zipper on top. The zipper does not allow it to be 100% waterproof but I have been using wet bags for years for bathing suits and diapers and nothing has come out that I wanted to stay inside. ;)
This is the Sling Sister's description of their bags:
"Eco Friendly, Fun & Convenient!
Made from 100% cotton on the outside and 100% nylon with a polyurethane laminate on the inside, they are BPA and phlalate free.
The zippered openings make these reusable snack bags super easy for little hands to open and close!
When snack time is done, simply turn inside out to wipe or machine wash on cold / low dry as needed.
These little bags are also handy for storing ipods, cell phones etc. Or create your own on the go activity pack with crayons and stickers!"