Tuesday, May 10, 2011

Gear Review: Sea to Summit Reactor Bag Liner

The first thing you are going to say when you pull one of these out of its stuff sacks is, “No frickin way”… as in, “There is no frickin way this is going to add any warmth to my sleeping bag.” 

And I thought these things
smelled bad..................on the outside.
I’m here to tell you though, that what looks like black cheesecloth will actually hold heat beyond belief.  The thin black material is actually a proprietary fiber called Thermolite, otherwise known as “magic tauntaun hair”.

The magical qualities of this incredibly thin material were never more apparent to me than on a recent trip to Mt. Washington.  I had packed my thirty degree sleeping bag for what turned out to be a twenty degree night.  Not my brightest of decisions.

The Reactor saved me from disaster, though.  I could easily feel the difference in warmth when the liner was not pulled all the way up to my chin as I lay there at three o’clock in the morning waiting for the candy bar I had just eaten to help my metabolism kick into overdrive. 

Aside from the additional heat when an idiot packs the wrong sleeping bag, the liner increases the amount of time you can go between washings-- and consequently traumatizing your dog with the sound of tennis balls bouncing around in your dryer.

When you further consider that it can be used on is own for warm summer nights, it makes the $50 price tag palatable. 


  1. Nice review...I have carried one of these things in my pack for years but never used it....knowing that it adds so much warmth makes it feel like a nice safety net that is worth bringing along. Did you find that the liner was hard to get in and out of? Mine has no zipper so it is like getting into a big sock.

  2. Yes. Especially after a 2am pee break.