Expecting a cold night? This Thermolite liner (or sleeping bag liner) significantly increases the temperature of your sleeping bag. You can deduct more than 5°C from the comfort temperature of your sleeping bag. For example, if it can only be used at an ambient temperature of +10 °C, you should still enjoy a pleasantly warm night's sleep in your sleeping bag at +5°C. Furthermore, this liner, just like all other liners, will extend the life of your sleeping bag as you can minimise the number of washes your sleeping bag needs. The Ayacucho Thermolite liner easily whisks away perspiration and is extremely breathable and quick-drying. Use it inside your sleeping bag as a liner or as a sleeping bag in warm climates or during cabin trips. Highly recommended for any camping and hiking fanatic!