Sea to Summit Reactor Extreme Thermolite Liner

I went camping around Mt. Alexander (central Victoria) in early spring, temps would not have hit 0c but likely floated around 5c or so. In combination with a S2S Th2 5c bag I was surprisingly chilly in the early morning when it was coldest, certainly not comfortable but not freezing. I would be interested to know how/under what conditions S2S determine their stated +15c temperature improvement as I did not receive such an improvement.That said, it took some of the cool edge off, is roomy, is nice to the touch, packs small and is light. You're likely to gain more with a set of mid-tier top and bottom thermals than from this expensive liner, As such I can't really say this liner is good value even when discounted to $80.I can imagine it being a good summer bag ... MoreI went camping around Mt. Alexander (central Victoria) in early spring, temps would not have hit 0c but likely floated around 5c or so. In combination with a S2S Th2 5c bag I was surprisingly chilly in the early morning when it was coldest, certainly not comfortable but not freezing. I would be interested to know how/under what conditions S2S determine their stated +15c temperature improvement as I did not receive such an improvement.That said, it took some of the cool edge off, is roomy, is nice to the touch, packs small and is light. You're likely to gain more with a set of mid-tier top and bottom thermals than from this expensive liner, As such I can't really say this liner is good value even when discounted to $80.I can imagine it being a good summer bag though!DO NOT take this out expecting it to turn your 3 season bag into a 4 season bag or even a 2 season bag into a early spring/later autumn bag, this may be obvious to the experienced campers but it's important to hold companies' marketing to account and this item is advertised as adding 15C to the comfort of your sleeping bag. If you've got the money, then it may be good insurance you can throw in the boot of your car or small pocket of your pack in case the temp dips a touch lower than you planned.

I bought mine on sale and am happy with the purchase. I've used this liner for a couple of years now for occasional spring, summer and fall camping/cottage living. I view it as a functional, warmer version of a typical sleeping bag liner. In very warm weather, I can use it as a standalone cover (sort of like being in bed with just a sheet over you). But it does not give 15 degrees C of extra warmth to the sleeping bag as the weather gets colder. For instance, I cannot imagine it turning a 10 degree C bag into a -5 degree bag. The regular price seems a bit high for what you get, especially considering that it is made in China. I have not used it for backpacking where weight is more of a concern.

Seems to work pretty well. I don't know for certain if it really added warmth in subfreezing conditions (used on a three-day, 60 mile trip where temperatures dipped below 30°F at roughly 5,500 feet) but I will say, combined with a 20°F down quilt, I stayed toasty warm and had some remarkable sleep.Night 1 I used it and the wind was howling. I had the vents opened on my tent but the vestibules closed. I was next to a creek and there was a bunch of snow on the ground (but not snowing) and not much protection around me to deflect wind this night. This night I was all bundled up, wearing a puffy jacket, beanie and mid-layer. However, I wasn't wearing socks and I did not experience cold feet.Night 2 I used it and I stayed at a camp spot in the dense forest and it ... MoreSeems to work pretty well. I don't know for certain if it really added warmth in subfreezing conditions (used on a three-day, 60 mile trip where temperatures dipped below 30°F at roughly 5,500 feet) but I will say, combined with a 20°F down quilt, I stayed toasty warm and had some remarkable sleep.Night 1 I used it and the wind was howling. I had the vents opened on my tent but the vestibules closed. I was next to a creek and there was a bunch of snow on the ground (but not snowing) and not much protection around me to deflect wind this night. This night I was all bundled up, wearing a puffy jacket, beanie and mid-layer. However, I wasn't wearing socks and I did not experience cold feet.Night 2 I used it and I stayed at a camp spot in the dense forest and it wasn't as cold as the previous night (though still pretty cold, probably mid-30°Fs). I was only wearing my tights and my compression long-sleeved base layer, as I got way too warm with the puffy jacket on. Also removed my beanie and socks because I got too warm. Slept like a baby. As a matter of fact, I slept in until 10:00am the next morning (which is way out of the norm for me, normally I'm up at 6:00am when backcountry hiking).All in all, I am convinced it made me warmer, but to what degree (no pun intended)? Not exactly sure as it's hard to give an answer, but what stood out to me was how comfortable it was to use. It felt great on my skin and made it feel like I was in a proper bed as opposed to that sticky, plasticky feel of my down quilt.Summary:PROS:- Very comfortable on the skin- I am convinced it did make my sleep system a bit warmer, particularly on my feet- Easy to wash, and just the fact that it is machine-washable is a great featureOTHER CONSIDERATIONS:- Heavy. There are lower-weight options on the market, but less weight could mean less warmth.- Does not pack down small. Again, this is a winter sleeping accessory so I don't necessarily consider this a bad thing, but just something to consider.- Very long. Knew this getting it, but it's far too long for me and I don't find the hood on it to be very useful. I'll probably have the hood removed and the entire liner cut to my height to make it pack down smaller/weigh less.Overall, for colder conditions, would strongly recommend.