Marmot has a long history of providing excellent quality products for those who like to get outside and explore the elements. The Marmot Nanowave 45 sleeping bag is no exception. This three-season sleeping bag is design with state of the art technology called SpiraFil. SpiraFil is a type of synthetic insulation that includes a unique blend of large, hollow, spiral fibers and small polyester fibers. Combined, these elements will keep users comfortable, warm and dry.