The Thermolite Reactor Fleece sleeping bag liner is a luxuriously soft and super warm liner that can bump up the warmth of your sleeping bag considerably. It also used as a stand-alone sleeping bag in winter climates and has a quarter length zipper to control temperature and allows the user to get in and out of easily. The hollow core fibers that make up this fabric trap heat effectively, keeping you toasty warm. Adds up to 32°F / 18°C of warmth to a sleeping bag Technical mummy shape with one hand, easy to operate, drawstring hood Quarter zip makes it easy to get in and out Can be used as a stand-alone sleeping bag in warmer temperatures Packs into its own Ultra-Sil stuff sack Weight : 14.8 oz Size : OS Colour : Mummy