Design and Details: Reactor Liner provides exceptional warmth, versatility and the freedom of movement in stretch knit comfort Add warmth to your sleep system in cool or cold conditions: with reactor liner Using Thermolite(R) Pro fabric with infra red-absorbing ceramic pigments Thermolite(R) EcoMade fibres takes thermal performance to the next level Stretch-knit fabric provides optimal comfort, and ensures the reactor fits any sleeping bag