Sleeping Options / Sea To Summit Thermolite Reactor Extreme Liner

Will:

I (and others) have written about this. The ridiculously named "Thermolite Reactor" is so thin that you can almost see through it — and despite the marketing hype (I call it outright lying) — it adds about 3-5F in warmth tops!!

I bought the thing a few years ago because I really wanted to believe the hype. After freezing my tail off one night (I had to cut the trip short because I didn't want to freeze for a second night) — I did a more sober analysis/comparison:

Take two first rate, high fill power down bags:

WM Ultralite – 20F – 28oz (16oz fill wt)
WM Antelope – 5F – 39oz (26oz fill wt)

If WM needs to add 10oz of the highest fill power goose down to boost 15F warmth, you really think an almost paper thin synthetic liner will cut it?? If that were true, none of us would ever buy winter bags — why, we would just buy a 3-season bag plus a Reactor liner!

Alas, the Reactor is pure fantasy. And shame on Sea-to-Summit!!

Just FWIW… I found myself more tangled up in mine. I would wear the wool baselayer instead of a liner. At least if you have to get up in the morning or go out at night… you get to keep the liner on by wearing the base layer.

I returned mine… I no longer advise liners.

Thanks for the quick reply Ben. I don't like hearing it, but its good to know. Darn false advertising!

Wallace – Makes sense, I was thinking I would probably be wearing full long underwear too.

I had one for a few nights, but returned it due to the above-mentioned tendency to bunch and twist…I did feel some measure of increased warmth, but nowhere near the claimed rating.

A liner is good to protect the bag from dirt and oils. It rarely seems to add any extra warmth beyond about 5 degrees.

"I was thinking I would probably be wearing full long underwear too."

This is the best way to add warmth, assuming you get real "long underwear". I.e. no cotton allowed. I would get at least some good capilene 3, but my preferred base layer is Merino Wool, yes it is expensive, but it is magic (besides, if you have a Nunatak you are no stranger to spending money). No, really… I think it must be magic. What else keeps you warm when its cold, cool when its hot, weighs so little, feels so good and doesn't stink after a 5 day hike?