Based on the success of our Compression Dry Sack, weve made a lighter version from 30D Ultra-Sil . We retained all the clever functionality of the original design with all the lightweight touches of our Ultra-Sil technology. The Ultra-Sil Compression Dry Sack compresses gear to one-third the volume while keeping it dry. All seams are waterproof, double stitched and fully tape sealed. These sacks feature a waterproof and air-permeable eVent fabric base with hypalon closure that does not wick moisture.