Sea to Summit introduces "Reactor", a Thermolite® sleeping bag liner. The fabric for this liner is DuPontGÇÖs 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 it's weight and remains extremely breathable. So, it's 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. It's very light and compact weighing just 8 oz (190 grams) and the packs into its own 3" x 5" siliconised nylon stuff sack.