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The THERMOLITE® Reactor™ Extreme liner is Sea to Summit’s warmest knitted sleeping bag liner. If your adventures take you to colder climates, the Reactor Extreme will add plenty of warmth to a sleeping bag. In warmer weather, it can be used a ‘stand alone’ sleeping bag.
The hollow core fibers of the THERMOLITE® fabric work like hollow polar bear or caribou fur – along with the knitted structure, this traps plenty of insulating air. Super soft and amazingly stretchy, the Reactor Extreme uses a heavier version of THERMOLITE® to provide extra warmth for an incredibly comfortable night’s sleep.
Use one to build your cooler-weather sleep system and to help to keep your sleeping bag clean, too.
Verified Reviewer
Reviewed at
Turns up the heat instantly worth the extra weight
Verified Reviewer
Reviewed at
My bag is only comfortable to mid-forties so I was glad to have this on nights in the thirties. Unlike an earlier reviewer, I found it easily fits back into its stuff bag, stuffing it in like a sleeping bag rather than trying to fold and pack it in. It was also nice to have this light thing to wrap around me while overnighting in an airport :)
Verified Reviewer
Reviewed at
I bought the Sea to Summit Reactor Extreme Thermolite Sleeping Bag Liner to use inside a (down) bag for sub zero weather. It's soft and lightweight and comfy. Unfortunately, the sleeping bag I had was kinda drafty and unusable in sub zero temps....so I ended up using the liner during much milder weather....seriously, just the liner alone. I love how it packs down so small in size. I stashed it in my vehicle, for backseat naps during long trips in milder temps (and with a wool blanket when it gets a little cooler). This liner provides a little bit of extra warmth...I think the word "Extreme" in this product's title is inaccurate, though, lol! What would make it Perfect would be a zipper, to make it easier to in and get out of. A zipper with a protective thermolite cover flap, please.
Verified Reviewer
Reviewed at
This liner is awesome. I have the thermolite reactor, that I also bought from LLBean, which only gives up to 14 degrees in warmth, and I love it. I needed another one for my daughter since we were going on winter camping trips and her fleece liner wasn't cutting it. This liner proved to be the way to go, especially since I really like the other one I have. My daughter loved how small it packed up and it didn't take a lot of room in her pack or add on a lot of weight. She was really warm all night. I would highly recommend this to anyone who is doing camping in the cold and wants an extra layer of warmth without sacrificing additional space or weight on your pack.
Verified Reviewer
Reviewed at
I found this to be large and comfortable. The reason I chose this particular model from Sea and Summit was because I am specifically using it to increase the warmth of one particular light weight sleeping bag. It will also be a liner to keep my other sleeping bags clean. You do need to crawl in from the top but I am used to that. Since there is no opening on the side it keeps you warmer.
Verified Reviewer
Reviewed at
This bag does do a good job of keeping you warm. But when you get into your sleeping bag you sit down on it, get your legs in and then zip it up to the comfort level you desire. However, using this liner you cannot operate that way because it doesn't have a zipper. You must put yourself into it from top to bottom as it is actually a giant sock! Once you do that your hands/arms are restricted when getting into your regular bag. Also, if you need to move around or get out for a potty break the frustration just gets worse as you have to wrangle your arms up out of the top of this liner, then operate your bag zipper. After that you have to stand up so the liner falls to your feet before you are free of it. I'll be finding a seamstress that can add a zipper at least 3/4 the way down the top. Otherwise, this liner feels like being in a trap. Find one with a zipper and don't get this one.
Verified Reviewer
Reviewed at
For the first time with temps below freezing, I was warm! Highly recommend!
Verified Reviewer
Reviewed at
As an airline crew member, I use this sleeping bag liner rather than a bulky blanket in the crew bunks when working or in the cabin when I am a passenger. Standard blankets can slide off. With the bag liner, I can roll over and never lose my cover. When I am finished, I just stand up and drop it to the floor, then pack it in the small bag. It washes well too.
Verified Reviewer
Reviewed at
Super helpful way to add warmth without bulk. Really soft too!
Verified Reviewer
Reviewed at
In the store I placed my hand inside the bag and could feel the heat from my hand being radiated back to me; it felt very warm. In the field the bag works well, feels very cozy, and added about 10-15 degrees to my down bag. It was especially helpful in keeping my feet warm. And it's perfect as a warm weather sleeping bag on its own in weather over 60-65 degrees.
