Sea to Summit was the originator of the valve-free compression dry sack concept. This innovation uses an air-permeable base made of eVent® waterproof fabric, which allows air to be pushed out of the sack, but won't allow water to get back in. Ideal for sleeping bags and insulated clothing, the eVent Compression Dry sack is the original and still the best. Suitable to keep contents dry in any wet situation where the bag is not submerged. Read more at