Gear Review: Sea to Summit CoolMax Sleeping Bag Liner

The Sea to Summit CoolMax Adaptor Sleeping Bag Liner is both efficient and dependable. It offers a way to add some extra warmth to your sleep system without breaking the bank. I had the chance to take a silk liner out on the AT. While I found the silk to be more compact, the Coolmax Adaptor is more comfortable.

Sea to Summit markets this liner as a product that can be used by itself or as part of a layered system. Generally, it’s used to add extra warmth. But if you sleep warm, using just the liner for your sleep system is an option. A friend of mind used this liner during the warmer months on the AT as his blanket without complaint.

Compact-ability of the Coolmax Adaptor

MSRP: 47.95
Weight: 8.6 ounces
Pros: It adds about ten degrees. It’s super soft. And it’ll keeps the funk out of your bag for a while longer.
Cons: It’s slightly less packable than a silk liner.

Sleeping bag liner highlights

Draw cord

Coolmax Adaptor Draw Cord

Why opt for a liner?

Adding a sleeping bag liner to your set up brings your warmth level up a notch without forcing you to buy a full new bag. If you’re planning on taking your sleep system out for an extended hike, adding a liner during the cold nights might do the trick. And if you sleep warm, a sleeping bag liner might be enough to get you through the warm temps. And it’ll provide a bug barrier.

How other reviewers feel about the CoolMax Adaptor

Other reviewers have overwhelmingly positive things to say about the Coolmax Adaptor. Amazon gives it 4.5 stars, boasting great comfort.

CoolMax Adaptor Weight

This is not an insanely heavy product but there are lighter options. And the liner itself isn’t completely necessary to use as a layer in your sleep system. But it offers a nice layer of warmth.

Cost of the CoolMax Adaptor

It certainly doesn’t break the bank but camp gear isn’t cheap either. If your sleeping bag isn’t quite warm enough to take on the chilly temps, the adaptor offers a cost-effective solution.

Compare and Contrast Sleeping Bag Liners

Sea to Summit Reactor Thermolite Sleeping Bag Liner

MSRP: $57.95
Weight: 9 ounces

  • The difference: Adds about 14 degrees.
  • Better weight to warmth value (but at a cost)

Big Agnes Synthetic Sleeping Bag Liner

MSRP: 69.95
Weight: 9 ounces

  • Adds 10-15 degrees

Is this sleeping bag liner right for you?

Depending on your intended use, the Sea to Summit Coolmax Adaptor Sleeping Bag Liner compliments most sleep systems without you having to sell your soul. If your bag or quilt is already sufficiently warm for the environment you’ll be using it in, it’s not a complete necessity. But it offers a nice bug barrier.

Final Thoughts

While I had no complaints about using this sleeping bag liner while I was hiking the Appalachian Trail, I don’t think it’s a completely necessary part of your set up. Eventually your gear is going to stink, even if you take preventative measures.

Shop this Liner Here

Disclosure: This product was donated for the purpose of this review. But the generosity in no way affects my analysis and overall opinion of the product.

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Comments 1

  • Lando11 : Feb 14th

    I was recently preaching to some friends about the endless positives of a bag liner. I’ve had the same 1 for about 10 years(Sea to summit Reactor 10) and it is truly the only piece of gear I use on every overnight trip, regardless of season. From nights in the -20 range in the Adirondacks to hot & humid nights in the summer the thing is always being used. I haven’t used it in this way (yet) but is a highly practical scarf too.

    I’ve found the combo of bag liner and 30* hammock gear UQ is feather-weight sleeping system that I can use to nights as low as 45-50* without issue. In bug season, I’ll still use a net-less hammock (Grand trunk nano 7) and let my liner sort of work as a bug net.

    In summary, buy one and you won’t regret it for a second.


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