When a waterproof pack cover is this light (4 ounces), bringing it along is no hassle at all. It even comes with its own stuff sack. Made of 30D Diamond Ripstop Sil Cordura silicone-impregnated, waterproof finish can't peel or wear off over time. "No-seam" construction provides complete waterproofness. Keeper strap helps secure it to the pack and prevents the sides from catching wind as you hike. Mini-siliconized nylon stuff sack remains attached to the cover so it won't get lost. Fits packs 3,000-4,300 cu. in. (50-70 liters).