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  • Sea To Summit - Reactor Thermolite Sleeping Bag Liner - Black
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  • Sea To Summit - Reactor Thermolite Sleeping Bag Liner - Black

Sea To Summit Reactor Thermolite Sleeping Bag Liner


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    • Black

    38 Reviews


    Stay comfortable.

    Pack the Sea to Summit Reactor Thermolite Sleeping Bag Liner on trips where the weather could change drastically or for a night under the stars. This mummy shaped sleeping bad liner adds up to 15 degrees Fahrenheit to your sleeping bag and can keep you comfortable on a warm night by itself. The combination of its low weight and high compressibility makes it a painless addition to your camping quiver.

    • Liner adds fifteen degrees to mummy sleeping bags
    • Thermolite is lighter and warmer than fleece
    • Drawcord around hood cinches for secure coverage
    • Item #STS0085

    Tech Specs

    Degrees Added
    15 F
    Claimed Weight
    9 oz
    Recommended Use
    camping, backpacking
    Manufacturer Warranty

    Tech Specs

    • Reviews
    • Q & A

    What do you think about this product?

    Have questions about this product?

    Nice and comfy

    • Familiarity: I've used it once or twice and have initial impressions

    I wanted a sleeping bag liner that would keep me a little warmer, without restricting me inside my sleeping bag. This is great! I have the Klymit KSB bag and I love the stretch it has. This liner works amazingly with it. I'm able to stretch out how I like and still feel nice and warm. It has a hood that comes up and over your head which is a nice bonus. I am taking it on a camping trip this weekend and will see if it keeps me warmer!

    perfect addition for the colder nights

    • Familiarity: I've used it several times

    If you don't do a lot of cold weather camping, it's great to add this is the mix instead of buying another sleeping bag.

    Saved me on a cold night in Africa

    • Familiarity: I've used it several times

    This liner really made a difference on a cold night on a recent trek. I had a zero degree bag but still needed a little extra warmth to stay comfortable. This thing was exactly what I needed. Light, comfortable, and really does add that extra 15 degrees of warmth. It's also so small when packed that it's not really a sacrifice to add it to your pack. I feel like this actually prevents me from needing an additional sleeping bag too. Oh and when you are staying in a sketchy hostile, it comes in handy if you don't want to risk sleeping in dirty sheets!

    Great addition to your bag

    • Familiarity: I've used it several times

    I have used this liner a few times in my sleeping bag to help give me a few extra degrees of warmth if my normal summer bag is rated at a higher temp than what I will be camping in. I have also used this liner as a sleeping bag on its own while down in Costa Rica staying at hostels. Normally I did not need it but some times it would get colder and I would use this and it was perfect. It also helps keep the inside of your sleeping bag a lot cleaner too which is a bonus.

    Super Comfy and Warm

    • Familiarity: I've put it through the wringer

    I just got this and used it for a 20 day winter grand canyon river trip, where temps ranged from 20-35 degrees at night. This paired with my 15 degree bag kept me plenty warm every night, was super comfortable, and kept my sleeping bag clean. It packs down small and fits in my sleeping bag stuff sack. Over all I am extremely satisfied with this liner and would highly recommend!

    Look no Further

    • Familiarity: I've put it through the wringer

    This liner is the perfect addition of warmth without adding too much weight or bulk to your sleeping set up.

    On a 45-day expedition in the Arctic, this liner crucially boosted the warmth of my going-on-10-year-old sleeping bag. My bag was still able to fit in the same size stuff sack (sea to summit's eVent), which made packing each morning easy. I also love that this liner is easy to wash, keeping my down bag in better shape for more adventures ahead.
    The fabric is cut for more than enough room, and stretches nicely, so you'll never feel too constricted.

    Saved my bacon

    • Familiarity: I've used it several times

    I bought this to use with the sleeping bag I rented for my Mt. Kilimanjaro climb and it saved my bacon. The sleeping bag was missing the string to "mummy" the bag around my head, so it was often challenging to keep the warm in and the cold out. I mummied up in this insert and it helped keep me warm enough, especially at Barafu camp.

    Add that extra little warmth

    • Familiarity: I've used it several times

    I got this mostly for summer camping in the desert and to pair it with my down bag to add some warmth and protect the inside of my bag. I highly suggest this for anyone.

    Quality liner

    • Familiarity: I've used it once or twice and have initial impressions

    This sleeping bag liner is a great one. It will add about 15 degrees of warmth to any sleeping bag for those cold nights in the woods. I'd recommend this to anyone who tends to run a little colder, to insure that you don't get cold when you're out adventuring.

    Excellent liner to augment bag warmth

    • Familiarity: I've used it once or twice and have initial impressions

    This liner was purchased for a recent 3 day trip through Big Bend. I primarily brought it for my girlfriend who used it on the last two nights after she had a rough first night. She has stated that it was the difference between a cold, miserable, sleepless night to a wonderful night's sleep. The evening temperatures were probably around the upper 30's and she had a 20 degree bag.

    It is very soft, fairly light, and (according to my girlfriend) very helpful in increasing the temperature rating of your bag! I highly recommend for those who: A) Sleep a little cold B) hate grimy sleeping bags C) Hate the feeling of clammy nylon sleeping bags

    Toasty warm!

    • Familiarity: I've used it several times

    While this liner can't protect you from roaming can help you sleep like one! I used it on a Teton backcountry trip for added warmth. For a minute I thought I was in a 5 star hotel. It's soft, adds just enough warmth, and you can pack it anywhere!

    Good bag liner

    • Familiarity: I've used it several times

    Very happy with this bag liner. Good balance of weight, warmth and size. While the degree of warmth it adds is a bit subjective, to me it is a good 10 degrees. To address an earlier question, I am 6’4”, use a long bag and have no problem using this liner.

    Warm, comfortable, highly recommend

    • Familiarity: I've put it through the wringer

    I used this bag hiking in the Andes, and as promised it added approx. 15 degrees of warmth (I'm very surprised to read comments to the contrary below!!). Roomy, soft, with nice ties to hold it up around your shoulders. Will use this for years to come.

    Serves its purpose

    • Familiarity: I've used it several times

    I usually always sleep with a liner in my sleeping bag. They are much easier to clean than a sleeping bag. This is very light but adds 15 degrees to any bag, which after using I think is pretty accurate. Definitely worth purchasing if your looking for a little extra warmth for not a lot of money or weight. Also can be used on its own for light covering.

    Good and comfortable liner

      I always try to sleep with a sleeping bag liner to protect my down sleeping bags from sweat and oil. I bought this for winter camping and really like it. I would agree with the reviews below that 15 degrees is a bit generou. But I don't think 5-10 degree increase would be out of line. Overall, I like the liner a lot and it doens't seem to be showing any signs of wear despite numerous uses/washes.

      Not that great

        This liner is alright but it really doesn't add as much warmth as it claims. If you open it up you will see why, you can see right through it. The fabric is stretchy and comfortable but with no zipper or any type of opening you have to shimmy your way into from the top which is annoying. I traded it is for an Alps microfiber liner that weighs and packs about the same, but has a velcro opening about half the length of it which is much much easier to get into and actually adds more that a few degrees of warmth.

        I wasn't a fan of the sea to summit one. I would have to say the ALPS was a better purchase because it is smaller and lighter and I got it for about 1/3 the cost of this one. I returned the the sea to summit one.

        How cold could it be outside to use it...

        How cold could it be outside to use it without a bag and still be comfortable?

        Does this liner have zipper. How easy is...

        Does this liner have zipper. How easy is it to get into. I wanna use it for wall climbing but if its to hard to get into its a hassle.

        I'm about the do the Annapurna trail and...

        I'm about the do the Annapurna trail and the Everest base camp trek in Nepal (huts with beds, but freezing nights). Do you think this will do (in addition to some blankets) or there is no escape from taking a sleeping bag?
        I'm a guy, who usually is OK with mild & cold weather.