Outdoor Research Airpurge Dry Compression Sack 20L 100% Nylon Fabric Performance: Waterproof, Air-Permeable Panel, Compressible, Durable, Fully Seam-Taped Design Features: Roll-Top Closure, Buckled Lid, Compression Straps, Webbing Handle On Bottom Functional Details: Air-Permeable Band Allows Evacuation of Air Air permeable/waterproof fabric band purges air during compression Hydroseal coated nylon is waterproof and durable Waterproof taped seams Internal zippered pocket doubles as small item and stuff sack storage