Sea to Summit Thermolite Reactor Extreme Sea to Summit Thermolite Reactor Extreme
Related Sea to Summit Thermolite Reactor Extreme 4

Sometimes you just need that little extra bit of warmth but don’t want to invest in a new sleeping bag. We were stuck with this issue recently. We are constantly on the move, one week we can be in summer conditions and the next week we might climb into the mountains and it can be down into the 30’s at night. We love our sleeping bags but we weren’t quite as comfortable as we would like to be on the colder evenings. We contacted Sea to Summit and they were kind enough to send us a couple of their Thermolite Reactor Extreme Mummy Liners to test. Overall we have been very happy with the liners.

Using a liner is great for a few reasons. First off, it keeps your sleeping bag clean! It’s a pain to wash a bag and we are not always the cleanest when we head to the tent after a long day of riding. The more we use the Sea to Summit liners the cleaner our bags have stayed. When the liner gets dirty it is super easy to throw in the wash with our clothes. We also love these liners because as you move while you sleep the liner moves with you keeping the areas closest to you warm. Devon found this a huge plus! Her bag is slightly large for her, so when she moved in the middle of the night parts of the sleeping bag would still be cold making her very uncomfortable. With the liner she is warm and comfortable through the night. She uses it well more than half of the nights, warm or cold, for this reason. The Thermolite liners are also extremely soft and comfortable. It’s a nice change from the synthetic sleeping bag material and feels much similar to sleeping in a bed with sheets!

In addition to adding a significant amount of comfort and warmth to our bags, we also love that we can use the liner on its own for the nights when it’s just to hot to get in our down sacks. No more sticky nights! The liner is perfect just on its own and it even has a pull string so you can tighten the top as needed. I could definitely use this for a summer bag.

While the liner is fairly light, it is actually rather large when packed down and amounts to about ¼ the size of our compressed sleeping bags. So it is important to take this into account if volume is an issue.

The +25 degree rating, we thought this was a bit high. In reality it felt more like an addition of 10-15 degrees Fahrenheit. We certainly noticed we were much warmer using the liner but I felt much of this added comfort was gained because the liner moves with you so your body doesn’t have to re-warm parts of the sleeping bag as you move.

Sea to Summit was extremely generous to send us these liners to add to our sleeping system. We cannot thank them enough for their continued support!

Adding a Sea to Summit liner to your sleeping system is certainly something I would recommend. It does a great job of extending the usable range of your bag. Not only will you be much warmer and more comfortable on the colder nights but you will also have a great option for the hot nights. Sea to Summit also offers a range of bag liners for various degrees of added warmth.
  • keeps bag clean
  • warmth moves with you
  • warm weather sleeping bag/more options when its warm or cold
  • comfy
  • 1/4 the size of sleeping bag packed
  • not quite +25 degrees

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5 of 5

4 of 5

4 of 5


“Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming "Wow! What a Ride!”