What Our Gearhead(R) Experts Are Saying:"I started using the UL Recovery Sleeping Bag Liner on multi-day trips, and it really changed how rested I feel after a night out. It's light, compact, and the Celliant fabric actually makes a noticeable difference in warmth and recovery. Bonus-it keeps my bag cleaner for longer too."When we're pushing hard on trail and rest is our greatest asset, we want every advantage we can get. The Big Agnes UL Recovery Sleeping Bag Liner is built for better sleep and faster recovery, integrating Celliant(R) bioceramic fabric technology to help convert body heat into infrared energy-boosting circulation and improving rest after long days in the backcountry. We pack this liner for its comfort and performance, but also for its versatility. It adds warmth to any sleep system, protects our bag from wear, and can even be used on its own during warm-weather overnights. The smooth recycled polyester fabric feels soft next to skin, and the whole thing stuffs down small when it's time to move out. After big efforts and big miles, this liner helps us recharge for the next day's adventure.