The lightweight, inflatable Cumulus Pillow features an ergonomic design that provides proper support for your head and neck during sleep, plus Spirafil™ high-loft insulation for added comfort. This unique blend of large, spiral hollow fibers and small polyester fibers provides the exceptional warmth, softness, and compressibility of natural down while increasing moisture resistance. It weighs in at just 4.3 ounces and compresses into an included stuff sack, making it a great choice for minimizing pack weight. A single locking air valve provides easy inflation as well as the option to make fine adjustments to firmness by letting out a little air at a time. It's constructed from durable polyester with welded seams for enhanced toughness, and the washable, brushed tricot pillow cover protects your skin from scratching.