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 squeezed out but water can't get 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. It employs waterproof seams, a hypalon roll-top, non-wicking closure and is super lightweight. The Sea to Summit Ultra-Sil Compression Dry Sack uses an Lightweight Ultra-Sil eVent® fabric base to allow air to be squeezed out. Ideal for packing inside a backpack or bike bag for all lightweight pursuits. Ultra-Sil™ 30D siliconized high-tenacity Cordura® nylon fabric for exceptional strength. Ultra-Sil™ fabric has a 2,000mm hydrostatic waterhead. Waterproof seams, double stitched and fully tape sealed. Waterproof and air permeable eVent fabric base. Hypalon closure does not wick moisture. Reinforced stitching on all stress points. Air compresses out, water cannot get in.