The Sea to Summit Thermolite Reactor Sleeping Bag Liner allows you to increase the warmth of your sleeping bag and your sleeping comfort.
Sea to Summit says:
Our most popular sleeping bag liner! The Reactor is made from 80g/m² THERMOLITE®—the lightest weight THERMOLITE® fabric available. THERMOLITE® is a hollow core fibre that provides amazing warmth for its weight and remains extremely breathable. The Reactor adds up to 8°C of warmth to your sleeping bag or can be used alone as a warm weather bag.
The liner is made from Du Pont Thermalite fabric, this is a hollow core fibre that provides maximum insulation for weight. If you want a liner to keep your bag clean then this must be a consideration as it offers an insulation upgrade at the same time.
Could be used on its own if camping in a warm climate.