Ultra-Sil Pack Cover - XS - 15L to 30LSea to Summit
This pack cover uses a "no seam" construction for complete waterproofness. It is made of 30D Diamond Ripstop silicone impregnated Cordura, so its waterproof finish can't peel or wear off over time. Siliconized Cordura is about one third the weight of traditional coated nylon. Rounding out the design is a mid-back keeper strap that helps secure the cover to the pack and keeps the sides from catching the wind (except size XS).