Cocoon MummyLiner CoolMax

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Cocoon MummyLiner CoolMax -

The MummyLiner - Coolmax from Cocoon adds warmth and comfort to your sleeping bag, while protecting it from dirt and body oils. A MummyLiner will extend the life of your bag by eliminating the need for frequent washings, which is how most bags are damaged. CoolMax is the fastest drying moisture management fabric. Its four-channel fibers move sweat away from the body.
Cocoon MummyLiners are specially designed to fit any tapered mummy sleeping bag. They feature a drawstring hood, a boxed foot-end and are double stiched for durability. On a hot night, your MummyLiner might be all you need.


  • Cocoon MummyLiners are specially designed to fit any tapered mummy sleeping bag.


  • CoolMax is the fastest drying moisture management fabric.
  • Completely double-stitched

Wash and Care:

  • Keeps your bag clean, saving it from the wear and tear inflicted by washing machines


  • Adds insulation and comfort


  • They feature a drawstring hood


  • CoolMax is highly breathable and easy to care for
  • Superior moisture wicking system


  • Wide top opening
  • 9.0 oz
  • Sleeping bag in warm climates
  • Sleeping bag liner for mummy-shaped sleeping bags
  • Its four-channel fibers move sweat away from the body.
  • On a hot night, your MummyLiner might be all you need.
  • A MummyLiner™ is an extremely lightweight tapered sleeping bag liner
  • 10.8oz.
  • Width tapers from 32" at the shoulder to 24" at the foot
  • 100%CoolMax®
  • 86" x 33"/24"
  • A boxed foot-end and are double stiched for durability
  • Comes with stuff sack for convenient packing
  • Adds approximately 8 degrees of warmth to your sleeping bag
  • +8.4°F
  • Perfect for wet or humid destinations
Backcountry Edge

Adding additional warmth (8.4 degrees Fahrenheit) and increasing the longevity of your sleeping bag, the Cocoon MummyLiner CoolMax is a tapered bag liner. On balmy nights, the MummyLiner CoolMax may be all the coverage you need. Wicking, fast-drying CoolMax fabric makes this especially ideal for humid climates.

Cocoon Mummy Liners are tapered sleeping bag liners to add warmth and comfort to any mummy bag. Easy to wash, Mummy Liners extend the life of your bag by protecting it from dirt and body oils. Features drawstring hood, boxed foot end, double stitched, and nylon stuff sack.


Add comfort to your mummy bag with this breathable, moisture-wicking CoolMax® liner.


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Average Price History: Price History
Review RatingNumber of Reviews
Added warmth (C):Up to 2.8 degrees
Added warmth (F):Up to 5 degrees
Dimensions:86 x 32(shoulder) x 24(at foot) inches
Item Weight:9.0 oz
Material:CoolMax polyester
Other:Stuff Sack Included
Recommended Use:General Backpacking
Shell Material:CoolMax
Size:86" x 33" tapering to 22".
Sleeping bag shape:Mummy
Stuff sack size:3.5 x 7 inches
Stuff size:3" x 6"
Temperature Rating:Adds 8.4 Degrees F
Type:Mummy-Shaped Sleeping Bag Liner
Upc, Ean, Isbn:799696106065
Weight:255 g / 9 oz
Weight - metric:0.26 kilograms
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Cocoon MummyLiner CoolMax Reviews:

Positive Reviews:

It actually does work!

I bought this liner on a whim to keep my bags (and my little son's) clean. It turns out that this thin little "baggy" actually does add a bit of heat retention. I was pleasantly surprised that it actually kept me warmer than I'd thought, even though I still plan to buy a warmer liner so I don't need to buy a more expensive bag.

I'm a bit confused why the call it CoolMax... I expected it'd only be good to keep the bag clean and absorb sweat when it's hot, but it actually does more. Unfortunately, I didn't have it along when I really needed it on the PCT during a storm at 32.5 degrees, so I can't comment on how it performs when wet (EVERYTHING was wet, even the tent was raining on the inside).

The material appears pretty thin and sensitive, and I imagine it'd be pretty easy to rip it, but I'm pretty careful and haven't had an issue yet. Some folks complain that the only way in is from the top, so here's what I do: I carefully put the liner on like a pair of pants (but up under my shoulders), then I slip into my bag like everyone else, and then sit up and adjust the liner and then the bag. No problems for me.
HikingPapa at REI on 03/03/2010

I Love This Bag!

I love this little thing. At first I thought it was too flimsy; however, I beat the snot out of it and its still hanging in there!
The Pros:
1) This saved me in my Cat's Meow for two reasons. First, it gave me added warmth when the temps dropped and second, it kept my stink off the bag. No other way to put it: when you are showerless for several days and in the same clothes...this little bag will protect your much more expensive sleeping bag from your reek.
2) Light and easy to shove in your pack - can't say anymore there.
3) Was great for climbing into in the middle of the day when I wanted to read my book but it wasn't super cold out. I look forward to using this around my house in the winter.
The only con I could think of (but didn't warrant ditching the 5 stars):
You can't move around in it much. Since that isn't what I bought it for, that wasn't a consideration for me. I thought I should mention it though, as it might be a factor for someone else.
stacky at REI on 07/07/2011

Great for extra warmth!

Will not go into the cold woods without this item! It makes my +20 degree bag really +20 degrees! If you like to sleep in your briefs and not all your clothing this item will help you do that.

I started off a night in my briefs with temps in upper 30s. Around 3am the temp dropped to 26 degrees. I woke up some what chilled in my NF +20 synthetic bag. I slipped into the liner and stayed in just my briefs to see how it worked. WOW! I was toasty warm the rest of the night.

It's also nice to not have to slip into that cold nylon either.

Can't wait to use it for hot days instead of a big sleeping bag here in Texas.

If you sleep kind of cold, GET THIS ITEM! You will love it!
Lonestar at REI on 03/03/2009

Does what it's supposed to

We bought this liner for my down mummy bag, with the primary purpose of keeping the bag clean. As an added bonus, it also adds a couple of degrees to the bag's warmth. When the weather was too warm to be zipped in the down bag, the liner was the perfect lightweight blanket. It washed well after use, and seems to be good to go for the next trip. The material is a little thin, so I'm not sure how it will hold up over time, but so far, I'm very happy with it.
AirGuitarRockin at REI on 10/10/2013

I love this thing

Very nice liner. I bought this last minute as I had planned an early Spring camping trip and the temperature took a turn on me. I was afraid the 30 degree bag I had wouldn't be enough so I bought this. The liner made my mummy bag warmer and much more comfortable. Also it is easier to wash than trying to wash an entire mummy bag. I've used it twice now and can't believe I went this long without one. Packs up nice and tight for cramming in a backpack.
Joe the Man at REI on 04/04/2013

Great Comfort for a low price

I bought this product before heading out on a snow camping trip in my cat's meow sleeping bag, which is only rated to 20*F. I have to say that I would have been really uncomfortable without this. I'm amazed at how much heat and comfort can be contained with such a thin layer of fabric! It packs down pretty small and can be stuffed anywhere in a pack.

I would buy this again, and definitely recommend it!
MacGruber at REI on 02/02/2011

Keeps the bag clean, adds warmth

Bought two of these before we went on a month long road trip with 2/3 of the nights sleeping in this liner and a sleeping bag. The liner is very soft and comfortable and helped keep the bags clean! It's much easier to just toss the liner in the wash than the bag itself, so we could launder them in the middle of the long trip if they became stinky.
jjkirkendall at REI on 10/10/2013

Clean bag, comfy sleep

I regularly use sleeping bag liners, primarily to help keep my bags clean. This liner is very comfortable, stretching and comforming easily if tossing and turning is the order of the night. Have also used it by itself on warm summer nights. I would like to see an option for some kind of side opening. Climbing in or out from the top can be a little awkward.
gear nut at REI on 09/09/2007


I found this liner to be a great summer bag for early night time, offering a little coverage without making me sweat. It also turned out to double as a superb mosquito netting, though I suppose you could find a lighter net. I was happy with it in my average-weight pack, but I may rethink when I go UL.
Herbivore at REI on 07/07/2008

A must have

On a hot sticky midwestern night, this liner makes a world of difference. I start out in just the liner and as the night and I both cool off, I slide into my bag.
The liner moves with me, and gives me the most comfortable night in a bag I can remember.
MattMooney at REI on 06/06/2010

Negative Reviews:


Took this bag liner on the AT with me without trying it out first. Big mistake! It was the first thing I shed from my pack. It was like wearing a giant stretchy nylon stocking, severely restricting movement and comfort.
hikerchris at REI on 03/03/2008

Neutral Reviews:

Glad I bought this

Bought this in preparation for a cross country cycling trip next summer. I had a chance to break it in during RAGBRAI (Iowa) last month. On hot nights it was a perfect lightweight blanket - I did not even get in it. On cooler nights it was great by it self as a bag (though not always easy to get out of during the night.) I did not take my sleeping bag, so on cool nights I used the liner while wearing long sweat pants and wool long sleeved shirt. No problems down to 60 degrees.
TentBiker at REI on 08/08/2013