The REI dividend is a unique benefit of membership in the REI co-op. It's comprised of your member refund—typically 10% back on eligible purchases—and/or your REI Visa® card rebates.
Each March, active REI members and REI Visa cardholders who earned a rebate receive a refund in the form of an annual dividend notice.
Only active members receive annual dividend notices. To maintain your active status as an REI member, you need to make net merchandise or shipping purchases of at least $10 per year, unless you joined that year. Member numbers are issued in one name and only that person receives the member refund. Your number can be used by others in your family, but it cannot be transferred to someone else.
Sea to Summit Thermolite Reactor Extreme Mummy Bag Liner Specs
Up to 25 degrees
Up to 14 degrees
3 x 5 inches
84 x 36 inches
Sleeping bag shape
Added warmth (F)
Added warmth (C)
Stuff sack size
Weight - metric
Sea to Summit Thermolite Reactor Extreme Mummy Bag Liner
Loading Ratings & Reviews...
Sea to Summit Thermolite Reactor Extreme Mummy Bag Lineris rated4.0833out of5by24.
Rated5out of5byslammiamfromSaved my bacon23deg zissou bag, got wet...didn't have time to fluff properly. Caught in freak cold snap on top of GA mountain on AT...13degrees + hail/snow. Bag had lost some of it's insulating ability and I'm convinced this liner saved my butt. I had all of my dry layers on ( had rained all day ) w/bag but was shivering badly. Used liner, cinched it up tight around my shoulders ( key ), and sealed mummy bag. Cold, but got through night. Without this...I probably would have been hypothermic. It's lightweight insurance that you can keep in the bottom of your sleeping bag when you need it, and just stuff the whole thing in your pack. Highly recommended. Works great as sleeping sack if at a hostel ( reactor on top of bag ), or as a summer bag. Will always be part of my pack.
Date published: 2014-03-16
Rated4out of5byTXBennettfromGood but not greatTook this liner up Kilimanjaro and used it 6 out of 7 nights. Lowest temperature was roughly 15 degrees we slept in at base camp. This liner definitely helped keep warm and I noticed a good difference when placing my arms outside of the liner. However, +25 degrees is a stretch. I would say 10-15 degrees is the best addition to a sleeping bag you'll get. It just seems too thin. However, it is very light, packs down very small, and pretty comfortable. If survival is an issue, you're likely going to get more warmth from a simple reflective emergency blanket that is 1/60 of the cost of this liner. It is hard to recommend this, but there is very little alternative to add warmth without adding layers or purchasing a warmer bag. Using a fleece liner is not an option when weight and packability is a must. I think there is a real gap in the warm bag liner market at the moment. This tries to fill that gap, but only does a satisfactory job.
Date published: 2014-03-15
Rated5out of5bySmoldering socksfromMust have!Tried this extreme liner in my 15 degree B.A. Lost ranger bag on a trip to kinsman pond last weekend. Temps were around 18 with wind and blowing snow, roughly -20 or so with the wind chill, and this liner made my bag perfect to sleep in, I was actually so warm I had to unzip and air out the bag to keep from being too warm. The liner was very easy to pack in with the sleeping bag or leave it in its own bag
Date published: 2014-02-07
Rated4out of5bydave124fromAdds WarmthUsed this with my old Squall North Face sleeping bag. When temps got down to 22 degrees, I was happy to have this liner around me. It didn't do much to insulate me from the cold ground but I don't think it is designed for insulation from ground freeze. Use this with a good sleeping bag along with a good ground pad and you'll be happy.
Date published: 2013-11-12
Rated4out of5byDJ ChapmanfromGets the job doneUsed it with a 20 degree bag in 19 degree weather. Slept comfortably through the night.
Date published: 2013-10-09
Rated5out of5byArboRafterfromLight, comfortable and effectiveIt filled the need at temps between the comfort range of my summer bag and when I would turn to my winder bag. It didn't twist up inside my bag and was very comfortable to sleep in. It was also easier to clean than my
down back would be.
Date published: 2013-09-05
Rated5out of5bygfonesfromGreat Product!!!Very light, very compact and fits well in it's included pack bag. This is with me at all times. Also keeps the dirt, sweat and oil out of the bag.
Date published: 2013-09-04
Rated1out of5bylou at poofromNopeI've looked at these bags at length with the idea of a stand alone bag, ultralight, with warm clothing as a booster for bike and ultralight hike trips.
So I finally made the plunge with the knowledge that I had the pickup to sleep in if all went wrong. Sigh.
I was out of the tent even before it was dark and into the truck cab for an awkward nights sleep. The bag could not keep me warm even in the truck.
I don't need a booster for my down bag. It does a wonderful job keeping me warm but its 2 pounds and this product is something less than a pound. So my experiment is at fail.
Get a light down bag and don't buy into this as a summer weight bag which is one of their claimed uses. Its not.
I returned this to my local REI. The staff there was friendly and their return service was great.
Date published: 2013-08-24
Ask a question and have it answered by REI product experts and fellow outdoor enthusiasts. Need immediate assistance? Use Live Help.
Loading Questions & Answers...
Sea to Summit Thermolite Reactor Extreme Mummy Bag Liner Customer Reviews