Add warmth to your sleep system in cool or cold conditions: with our Reactor Liner. Using Thermolite Pro fabric with infra red-absorbing ceramic pigments and Thermolite EcoMade fibers , the new Reactor takes thermal performance to the next level. The stretch-knit fabric provides optimal comfort, and ensures the Reactor fits any sleeping bag. Choose between the classic Mummy and the Mummy with Drawcord - the footbox opening offers plenty of ventilation and the versatility of walking around camp while still wearing your liner if needed.