Peregrine Ultralight Pack Cover Feautures Weatherproof cover for backpacks a must have for keeping a pack and its contents dry in rainy conditions. 30D CORDURA Ultralite fabric delivers a desirable combination of qualities: durable, compact, lightweight, and waterproof. Double waterproof treatment with a siliconized outside and a polyurethane coated inside. Bungee cord and keeper strap secures the cover completely over the backpack. Seamless construction eliminates the chance of water seeping through.