Keep cozy in cool or cold conditions with our Reactor Liner. Crafted with Thermolite® Pro fabric, featuring infrared-absorbing ceramic pigments and Thermolite® EcoMade fibers, the Reactor delivers next-level thermal performance. Its stretch-knit design ensures a comfortable fit in any sleeping bag. Available in the classic Mummy or the Mummy with Drawcord, the footbox opening provides ventilation and lets you move around camp while staying wrapped in warmth.