Add extra warmth to your sleep system in cool or cold conditions with the Sea to Summit Reactor Extreme Mummy Sleeping Bag Liner. Using infrared technology, the Reactor Liner provides exceptional warmth, versatility, and freedom of movement in stretch-knit comfort. This lightweight, 100% polyester mummy-shaped liner uses Thermolite Pro technology with hollow-core fibers and infrared ceramic pigments to reflect your body's heat, and will work seamlessly with any sleeping bag shape. Drawcord footbox offers plenty of ventilation; HeiQ Fresh odor control technology helps keep your liner fresh even with extended use. Mfrs. limited lifetime guarantee. 100% polyester Use inside your sleeping bag for extra warmth Efficient infrared technology reflects body heat Powered by Thermolite Pro technology Drawcord footbox for ventilation HeiQ Fresh odor control technology Fits any sleeping bag