~Hyperlite says~

Zippys are here to fool-proof your backpacking setup with 1, 2, and 3L volume options, sized right and easy to get into for things like a hygiene items, charger cables, bikepacking tools, ski hardware, your water filter, cookware bits and pieces, etc. They’re constructed with 100% waterproof Dyneema Composite Fabrics and a waterproof zipper, adding another layer of protection against moisture.