Sea to Summit's “Reactor” is made from the lightest weight Thermolite® that DuPont has yet approved. Thermolite® is a hollow core fiber that provides extraordinary warmth for its weight and remains extremely breathable. Adds up to 15 degrees of warmth to a sleeping bag or, used alone, is the ideal warm weather bag.

• Sea to Summit Reactor Thermolite Mummy Liner
• Lighter weight, more packable than fleece
• Adds up to 15 degrees of warmth to a sleeping bag
• Mummy shape with a box foot
• Draw cord hood with mini cord lock
• Color of liner is black
• Weighs just 9 oz
• Packs into its own 3” x 5” sil nylon stuff sack