Increases sleeping bag performance by up to 25°F (14°C) with super-insulating 110g/m² Thermolite® fabric. Thermolite® is a hollow core fiber that provides extraordinary warmth for its weight and remains extremely breathable. Spacious design allows for a comfortable night’s sleep, even when the mercury plummets. Perfect for extending the season of your sleeping bag.

Features:

• 110 g/m2 Thermolite® construction throughout
• Adds up 25°F (14°C) to warmth to a sleeping bag
• Mummy shape with a box foot
• Draw cord hood with mini cord lock
• Packs into its own Ultra-Sil™ stuff sack