Description of Sea to Summit eVent® Compression Dry Sacks A completely new concept in compression dry bags - there is no valve. 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. Features: Unique compression idea - allows air to be pushed out to compress, but water can’t get in because of the waterproof, air permeable eVent® fabric base Rugged 100 D nylon body & lid Waterproof seams - double stitched and tape sealed Roll top Hypalon™ closure with lid and 4 straps evenly compresses and maintains compressed size Reinforced stitching on all stress points Pull handle on the bottom Super compact and very light