When a waterproof pack cover is this light 4.6 ounces, bringing it along is no hassle at all. It even comes with its own stuff sack. Made of 30 denier Diamond Ripstop Sil CorduraAR 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 4,300 5,800 cu. in. 70 95 L.