Sea to Summit introduces Reactor, a Thermolite sleeping bag liner. The fabric for this liner is DuPonts Thermolite. It is the lightest weight Thermolite available and Sea to Summit is the first to use this new fabric in a sleeping bag liner. Thermolite is a hollow core fiber that provides extraordinary warmth for its weight and remains extremely breathable. So, its much more comfortable to sleep in and creates more warmth for its weight. The Reactor liner will add up to 15 degrees of warmth to a sleeping bag or can be used on its own as the ideal warm weather bag. Its very light and compact weighing just 8 oz 190 grams and the packs into its own 3 x 5 siliconised nylon stuff sack.