Western Mountaineerings Sonora and Tioga sleep liners are a great lightweight option for anyone looking for a compact and lightweight sleeping bag liner or sleep sack for travel. Both the Polyester (Sonora series) and the Silk (Tioga series) fabrics are soft, breathable, yet woven with ample density to help protect you from the questionable bedding in a sketchy motel room. Both materials feel very nice against the skin and will not latch onto other fabrics when used inside a sleeping bag or under some blankets in the loft of a winter cabin. These liners pack small enough to take along anywhere you travel, and using it in a sleeping bag will help to keep your bags lining material cleaner on extended backcountry outings. The mummy and taper liners are designed for maximum efficiency while the rectangular liners provide a bit of additional room for those who need it.