The Ultra-Sil™ Compression Dry Sack is a super lightweight dry sack designed to compress bulky clothing or other squishable gear that lives inside your pack. Made from Ultra-Sil™ 30D CORDURA® Nylon fabric with an eVent® fabric base, the air can be rolled out but can't get back in. It's an ideal option for use inside a backpack during longer lightweight hikes, adventure travels, cycle touring and any activity where you need to maximize pack space by compressing your bulky items to one-third of their volume. It employs waterproof seams, a hypalon roll-top, non-wicking closure and is super lightweight.