Back to top

Please select a color/color.


  • CoolMax® polyester provides moisture-wicking, quick-drying comfort and offers the lightweight, softness of cotton
  • Use it as a part of your sleep system or by itself as a warm weather 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
  • The Sea to Summit CoolMax® Adapter liner comes with a lightweight Ultra-Sil™ stuff sack

View all Sea to Summit Sleeping Bag Liners

REI membership


Best Use Backpacking
Sleeping Bag Shape Mummy
Added Warmth (F) Unavailable
Added Warmth (C) Unavailable
Stuff Sack Size 3 x 5 inches
Material(s) CoolMax polyester
Dimensions 82 x (shoulder) 36 x (foot) 12 inches
Weight 8.6 ounces
Weight - Metric 0.24 kilograms
Rated 5 out of 5 by from Summer shell or winter liner -- cool! The prospect of stuffing my bag in a triple-loader is daunting, so the idea of a sheet to protect my comforter from sleep sweat was more than appealing. i took a look at a few different liners, & this one's worked out well, keeping me cool in summer heat & keeping my bag from getting stinky! It's a snap to wash and dries so quickly I barely knew it was wet! It's not constricting, stretches quite well, & you can even sew up the opening with the eskimo cord if you need to feel snug as a bug! The stuffsack is compact & fits in just about any little crevice in your pack or duffel. Great deal!
Date published: 2011-06-14
Rated 5 out of 5 by from Great for long camping trips I work as a conservation biologist and spend months camping in the backcountry. I bought this about a year ago for a new position camping in high elevation rainforest. Conditions range from frigid to swampy and this product stays dry and comfortable through it all. I bought this originally to save wear-and-tear on company sleeping bags as well as providing another, thin layer for warm evenings. I have to say, after a solid year of use, it looks new and I still love it. I struggle with mildewy smells and damp fabrics from every outdoor gear/clothing I take (including top-of-the line brands) EXCEPT for this liner. I can't express how nice it is to slip into a cool, DRY liner after a day in the cold rain. I will also add that I am not one to write reviews let alone 5-star reviews. This one is worth it.
Date published: 2013-11-12
Rated 5 out of 5 by from Perfect for sticky summer nights! This liner worked great as a lightweight summer shell when it was too hot for a sleeping bag of any kind but I didn't want to sleep in just my clothes. Used inside a sleeping bag on cooler nights it kept me from getting sticky and sweaty - I'd usually wake up toasty warm, sometimes TOO warm, but never sticky with sweat, which was really nice. I think it definitely adds a little bit of insulation on colder nights - I am a cold sleeper and I normally use a 15 or 20˚ down bag and tend to get chilly without extra clothes on when it is cooler than about 40˚, but we unexpectedly encountered temps into the 30's on our last camping trip and I never once woke up cold using this liner. It also packs down to about the size of a softball so there's no reason not to bring it along. It's also more easily washable than your sleeping bag (and it even dries quickly when hand washed) and it's really nice to slip into something "clean" to sleep in after a long day of hiking when you don't have access to real laundry facilities.
Date published: 2012-12-30
Rated 5 out of 5 by from 2nd CoolMax liner I like this liner a lot. I've used it backpacking, often. It adds about 10 degrees of warmth to my bag and keeps my sleeping bag clean. I also use it when I stay in cabins as it feels good against my skin and I know it's clean... My first one has thinned over the years and has a number of holes, so I decided to get this one as a back-up. I could wish for it to be as light as the silk liner, though.
Date published: 2014-09-10
Rated 4 out of 5 by from Sleeping bag liner I bought this for a cruise and hotel stays. Sometimes when your driving across country and you are ready to stop some place on your route, you will find all the nice hotels are full. If you have to stay in a "by the hour hotel" or 1 star hotel this sleeping bag liner will come in handy.
Date published: 2014-02-21
Rated 3 out of 5 by from Ok products, but could be better It's OK products, for minimalist campaign style. If you comfort driven you should choose cotton / silk blend liner. More space and more comfortable. CollMax synthetic feel sticky (could be my specific opinion). Also this product is seriously overpriced!
Date published: 2013-09-05
Rated 1 out of 5 by from Not worth the money Certainly not what I expected. The liner could benefit from a zipper, getting in it isn't easy...especially if you're a bigger or taller person. The material is thin and feels cheap. Personally feel it's about $30 overpriced for what you get, not worth the money and found it to be more of a hindrance. Will be returning the two I bought from REI.
Date published: 2013-01-29
Rated 5 out of 5 by from Makes sleeping a breeze This is a great product that I recently purchased for a camping trip to Arizona! It made sleeping a breeze and provided good protection for my sleeping bag. It is constructed very well.
Date published: 2016-07-19
  • y_2017, m_6, d_23, h_2
  • bvseo_bulk, prod_bvrr, vn_bulk_1.0.0-hotfix-1
  • cp_1, bvpage1
  • co_hasreviews, tv_0, tr_8
  • loc_en_US, sid_797111, prod, sort_[SortEntry(order=RELEVANCE, direction=DESCENDING)]
  • clientName_rei-inc
  • bvseo_sdk, java_sdk, bvseo-4.0.0
  • CLOUD, getReviews, 100ms

can two of these be zipped together

Asked by: ExiledMainer
The CoolMax Adaptor Liner does not have a zipper so two cannot be zipped together.
Answered by: REIservice
Date published: 2017-04-06
  • y_2017, m_6, d_23, h_1CST
  • bvseo_bulk, prod_bvqa, vn_bulk_1.0.0-hotfix-1
  • cp_1, bvpage1
  • co_hasquestionsanswers, tq_1
  • loc_en_US, sid_797111, prod, sort_[SortEntry(order=NUM_ANSWERS, direction=DESCENDING)]
  • clientName_rei-inc
  • bvseo_sdk, java_sdk, bvseo-4.0.0
  • CLOUD, getContent, 40ms