Dry-Bag® acts as a type of sponge that attracts water in its tiny holes called capillaries. At low humidity conditions, only the smallest of holes will be filled with water vapour. As the humidity rises, the larger gaps begin to fill. So, at approx. 90-100% humidity, our Dry-Bag® retains moisture at full capacity. However, unlike a sponge, our Dry-Bag® remains completely dry, even at full capacity.