Designed primarily for comfort, the Silk Blend Liner adds warmth to your sleeping bag via the 72% ThermoliteA(R) Pro yarns with infra red technology, ThermoliteA(R) EcoMade fibers and 28% silk. The combination creates a soft, luxurious sleep environment. Two versions are available. The Rectangular with Pillow Sleeve has Comfort Stretch Panels along the seams to boost sleeping comfort. The Mummy version has practical shoulder openings which aid with temperature regulation. FEATURES A liner is the climate core of your sleep system - the Mummy Shaped Silk Blend liner adds warmth and a touch of luxury to your sleeping bag Rectangular with Pillow Sleeve is a great hygienic sleep sheet wherever you travel HeiQ odor control technology helps keep the liner fresh even after extended use Sea to Summit Guarantee is offered for the Lifetime of this product