Made with lightweight 30D Ultra Sil instead of traditional 70D nylon, the Ultra Sil Compression Dry Sacks are roughly half the weight but still offer all the clever functionality of the original Sea to Summit Compression Dry Sacks.. . Compresses gear to one third the volume while also keeping it dry. Waterproof seams are double stitched and fully tape sealed. Waterproof and air permeable eVent fabric allows air to be compressed out, and wont let water in. Roll top Hypalon closure with lid and four straps for even compression Hypalon closure does not wick moisture. Reinforced stitching on all stress points ensures long lasting durability. Maximum volume: 10 L. Minimum volume: 3.3 L.