Designed primarily for comfort, the Silk Blend Liner adds warmth to your sleeping bag via the 72% Thermolite® Pro yarns with infra red technology, Thermolite® EcoMade fibers and 28% silk. The combination creates a soft, luxurious sleep environment. The Rectangular with Pillow Sleeve has Comfort Stretch Panels along the seams to boost sleeping comfort. Ultralight Comfort — Silk Blend liner adds warmth and a touch of luxury to your sleeping bag. Comfort Stretch Panels — Allows for freedom of movement when you turn over in your sleep. Thermolite Pro — Thermolite Pro has engineered hollowed out fibers with the addition of permanent ceramic pigments that absorb the body's infrared rays and reflect them back to the wearer. 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.