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      Sea to Summit Thermolite Reactor Extreme Mummy Bag Liner

      This Sea to Summit Reactor Extreme mummy bag liner adds a few degrees of warmth and extends the life of your sleeping bag.
      • $67.95

      Item # 797114

      REI Members get back an estimated $6.80 on this item as part of their annual member refund.
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      • specs
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      • Constructed of insulating Thermolite® fabric, a hollow-core, breathable fiber that provides extraordinary warmth for its weight
      • Adds up to 25°F of warmth to a sleeping bag; can also be used as a summer ultralight sleeping bag
      • Liner helps keep the inside of your bag clean, saving it from the wear and tear of washings
      • Drawcord hood with mini cordlock cinches around face to hold warmth in
      • Mummy shaped liner features a 3D footbox providing plenty of room for feet
      • Comes with a lightweight Ultra-Sil™ stuff sack


      Sea to Summit Thermolite Reactor Extreme Mummy Bag Liner

      Specification Description
      Best use Backpacking
      Sleeping bag shape Mummy
      Added warmth (F) Up to 25 degrees
      Added warmth (C) Up to 14 degrees
      Stuff sack size 3 x 5 inches
      Material(s) Polyester
      Dimensions 84 x 36 inches
      Weight 14 ounces
      Weight - metric 0.39 kilograms
      Trademarked terms Thermolite

      Sea to Summit Thermolite Reactor Extreme Mummy Bag Liner

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      Rated 2out of5
      by fromLittle Help Reading the earlier reviews, I felt confident buying this product. However, I felt it contributed nothing to my sleep warmth. It probably does keep the bag a little cleaner. Also, it likely would not hurt to put this in your day pack with your emergency blanket. Just don't expect this to add any warmth to a cold night.
      Date published: 2011-02-19
      Rated 3out of5
      by fromNot a warm liner I purchased the Sea to Summit Thermolite Reactor Extreme Mummy Bag Liner from REI with the idea of increasing the warmth in my well used three season bag (When it was new, I believed it was rated as 15 degrees.) Even though I do not like cold weather camping I decided to spend last night in a SNP hut to see what, if any, warmth the liner could add to an older sleeping bag. I was sleeping on a REI Trekker pad, in med weight long underwear (top and bottom), a hat, and a fleece pullover. The temperature got down to about 20 degrees F and I was freezing. I found the Sea to Summit Thermolite Reactor Extreme Mummy Bag added little or no warmth to the sleeping bag. It did feel good and I'll keep it to try as a summer sleeping bag. The 3 rating is because it does keep the bag cleaner, it felt good, it did come with a stuff sack, you can use the draw string to close the bag around your head, and I am hoping it can be used as an ultra light summer sleeping bag. Incidentally, after I put on some more clothing, I toss a couple of Grabber Mega warmers in the sleeping bag with the liner and as soon as the warmers started to activate my legs and feet were comfortable the rest of the night.
      Date published: 2010-12-21
      Rated 4out of5
      by fromVery satisfied! Purchased this item for a REI trip to Peru this summer. Just spent 4 days "field-testing" it in the BWCA of northern Minnesota. Added to the warmth of my bag on the cool nights and took the clammy feeling away on the hot humid night. Was indeed money well spent.
      Date published: 2010-06-17
      Rated 4out of5
      by fromThin, Light, Easy to pack, and Warm I only have one bag that's rated at 40-45 degrees. Going on a mountaineering trip I needed a warmer bag, but money was tight. Camping on 3ft plus of snow at 5,000 ft in early May on the way to Mt. Stuart was very cold. Other people had between 20 degree and 0 degree bags. This liner helped me a lot. With my bag it performed almost as well as the 20 degree bag. It's very light and thin but does add around 25 degrees. It is very impressive. The value is pretty good too. I am gonna keep it in the car for travel and emergencies. It is nice to add range to your sleeping bag setup. It is hard to get the liner and bag to line up and fit well. Moving around can twist things up a bit. All in all it's pretty great.
      Date published: 2012-05-06
      Rated 4out of5
      by fromDecent Liner My girlfriend and I just used these liners on a chilly weekend in the Whites (NH). I was skeptical about how warm these liners would keep us with our budget-based, thin, "30 degree" bags (50 degrees is probably more accurate) Fortunately when the temp dropped into the high 30's overnight we stayed incredibly warm. Not sure how these would do with our bags if we got below freezing, but I'll post an additional review once I find out.
      Date published: 2010-09-18
      Rated 4out of5
      by fromgreat stuff I've never used it as a standalone bag, but always use it in combination with my sleeping bags for extra warmth and to keep the bags clean. I haven't tested in extremely cold conditions to push the "temperature rating", but would suggest to the negative reviewer below that the issue could've been with the new marmot sleeping bag not meeting its rating..
      Date published: 2010-10-06
      Rated 5out of5
      by fromGreat 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
      Rated 5out of5
      by fromIts a must have I got this liner almost on a whim but have since really used the heck out of it. In Summer is makes a great great light sleeping system. In Winter with temps dropping to single digits where I live I include it in my zero back for that extra warmth that makes it so much easier to deal with. I typically will pull the sack up about chest high so i have some foot wiggle room in it and stay very very warm. It is one product that truly does help the rating on your sleeping back improve. The regular bag liner works great with Big Agnes sleep system matress bags. I also use this as a tiny sleeping bag during the summer months when you really dont need one but in higher elevations it gets a bit of night chill on. I found this to be an excellent product.
      Date published: 2010-12-10

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