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Sea to Summit Reactor Extreme Sleeping Bag Liner, Standard

SKU: STSREBL MFR: A3208
$79.95
$89.95
Save: $10 (11%)

Key Features

  • Boost your sleeping bag's warmth with this Reactor Extreme sleeping bag liner.
  • Thermolite fabric adds serious degrees, making it ideal for cold weather camping.
  • Lightweight at just 12.8 oz, this sleeping bag liner won't weigh down your pack.
  • Fits campers up to 6'6" (78 inches), providing ample room inside your sleeping bag.
  • HeiQ Fresh odor control keeps your sleeping bag fresh on extended backpacking trips.
  • Compact pack size (5.9 x 3 x 4.7") saves valuable space in your hiking backpack.
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Questions & Answers

Reviews about this item

Review Summary

2025-07-05T20:00:00

Rated 5 out of 5

Great Sleeping Bag Liner

Used the bag liner for a week camping. Worked great. Definitely recommend your Sleeping Bag Liners. Very roomy.

Glenda C.

2025-05-21T20:00:00

Rated 5 out of 5

Worked great

I have a down quilt was getting cold drafts coming in and disrupting my sleep. I actually put the quilt inside the liner and I was super warm

John A.

2025-04-22T20:00:00

Rated 5 out of 5

High utility, low weight

Compact. Easy to deploy. Adds loads of warmth for a small footprint. This is a great, inexpensive option to add significant warmth and extend the temperature range of your sleep system. If you're camping in multiple temp ranges, this can allow you to use a lighter weight bag and then use the liner on cold nights. Sea to summit makes awesome kit, this is no exception.

Frostbite

2025-03-08T19:00:00

Rated 5 out of 5

Excellent liner

The mummy shape is very comfortable, and the materials feel high-quality.

Dorit h.

2025-03-08T19:00:00

Rated 4 out of 5

Soft and comfy

Soft and comfy

ANTHONY S.

2025-02-13T19:00:00

Rated 5 out of 5

Kept me warm in the polar vortex!

I was on an upper Grand Canyon river trip during the polar vortex in January, and purchased this liner in anticipation of that, since I only have a 20 degree sleeping bag. This liner did its job and kept me perfectly warm and cozy during the trip!! With the caveat that I also had a puffy blanket; if I hadn't, the liner may not have been quiiite warm enough (it got down to 10 degrees at night, according to my friend who brought a thermometer on the trip). But regardless, I would highly recommend it for cold weather camping! I also really liked the snap-closure arm holes, so I could have my arms free instead of them being mummified in the liner.

Heidi S.

2024-11-11T19:00:00

Rated 4 out of 5

Almost perfect extra warmth

This was a great addition to my Spark Ultralight sleeping bag to give me a bit of an insulation boost for a cooler weather backpacking trip. For my purpose, this was a much better option vs. buying a warmer sleeping bag. My only complaint is the opening at the bottom. Seriously, who needs that? I certainly have no interest in walking around camp in my sleeping bag liner. There are better ways to keep warm when not in my tent. The opening with the drawcord just adds unnecessary weight, cost and an opening for a draft. Drop the opening, sew it closed and it will be perfect.

Joe Z.

2024-10-28T20:00:00

Rated 5 out of 5

When temps get low, this

When temps get low, this liner is great to take the edge off of the cold air. Comfortable fabric. I am pleased with the results. Partner to a zero degree bag, it is exactly what I was looking for

Benjamin A.

2024-10-10T20:00:00

Rated 5 out of 5

Perfect Liner!

This liner is always with me, if I am not using to stay extra toasty in my bag, I use it as a pad sheet for sleeping on during the hot desert nights. Absolute must have for any serious outdoors person

Alex C.

2024-09-30T20:00:00

Rated 5 out of 5

reactor extreme really warms up the sleeping bag.

Just went on a 3 days camping trip using my traverse IIv -4 sleeping bag and this liner inside. I am always cold, but this liner really warmed up the bag and made it toasty. Waking up to -3 celsius in the morning, I didn't want to get up because it was so nice inside my bag, liner and tent. For me, I will get down booties though as my feet are never warm. Highly recommended and it is light and packs small.

Angela S.

2024-08-15T20:00:00

Rated 5 out of 5

The perfect addition to my gear!

Light weight and amazing warmth. I ordered this to add the additional warmth and my bag and it has exceeded my expectations!

Andrea D.

2024-08-10T20:00:00

Rated 5 out of 5

Enhance your sleeping system

Reactor sleeping bag liners are a must have, not only to protect the sleeping bag but to give added comfort and warmth. The reactor extreme really delivers and its design features, with the arm holes and base draw cord, make it functionally versatile and adaptable over a range of temperatures.

William P.

2024-07-25T20:00:00

Rated 5 out of 5

Toasty and feet accessible

Staying toasty on cold nights is critical for a good night sleep for me. The opening at the bottom allows me to have my feet out and still benefit from the extra warmth.

Laura P.

2024-04-30T20:00:00

Rated 5 out of 5

Great Warm Liner

Love that it's easy to pack, light and super warm. The texture is super soft too. Highly recommend as an extra layer for your sleeping bag! Perfect for super cold camping nights.

Jachunter

2024-04-26T20:00:00

Rated 5 out of 5

Warm

I received this product free, complimentary of influenster, in exchange for an honest review. Super high quality and warm LINER! Better than most actual sleeping bags and only a liner! This has motivated me to purchase a sleeping bag by Summit because of how nice and warm the liner is.

Tkeegz

2024-04-24T20:00:00

Rated 5 out of 5

Soft and Comfortable

Material is soft and durable, easy to bring along on a camping trip. Fits snug in the little bag it comes in. Its like laying in a soft comforting cocoon, I cant wait to use it when I go camping. Its breath-able and yet keeps you warm at the same time.

Zoejanereviews

2024-04-22T20:00:00

Rated 4 out of 5

Functionally accurate and warming

Went camping up at Yellowstone national park and this baby arrived in the mail just in time. While my friends were shivering at night and feeling the chill, I was toasty and warm. Also this was super easy just to clip into my pack and didn't have to be a hassle to bring with. Great device and I loved every minute of using it

Andy B.

2024-04-17T20:00:00

Rated 5 out of 5

Amazing and comfortable sleeping bag liner!

Truly impressed with the quality of this liner; perfect for campers and outdoor enthusiasts alike. Super lightweight but also relatively warm, so it'd make a great addition to your camping supplies. Could probably double as a sleeping bag in the summer! Overall, I definitely recommend.

Amandac1137

2024-04-15T20:00:00

Rated 5 out of 5

Quality and durable fabric

This sleeping bag liner packs up very small and is convenient to carry around. It is very lightweight and breathable but the material feels high quality. I didn't have any issue washing it. On its own it is not very warm, which is actually preferable here in a warmer climate, but it would definitely help to insulate in combination with a sleeping bag.

Marcyl7

2023-12-28T19:00:00

Rated 5 out of 5

Soft and Warm

Light weight, soft and warm. Should work great as an additional layer in my system.

Kevin

2023-12-27T19:00:00

Rated 5 out of 5

Cozy without being heavy

Cozy without being heavy

Jackie W.

2023-12-12T19:00:00

Rated 5 out of 5

Increased the warmth of my

Increased the warmth of my sleeping bag to get thru the cold fall nights.

Laura

2023-11-04T20:00:00

Rated 5 out of 5

Small, compact and under 1

Small, compact and under 1 pound. Feels nice on the skin. Anxious to try it with my 30 degree down bag.

Scott

2023-10-06T20:00:00

Rated 5 out of 5

Warm. Soft. Comfortable. Great addition

Warm. Soft. Comfortable. Great addition to shoulder season camping

Daniel

2023-09-12T20:00:00

Rated 5 out of 5

This item kept me warm

This item kept me warm when temps dropped substantially on an alaska moose hunt

Nicholas

2023-06-01T20:00:00

Rated 5 out of 5

Fits inside sleeping bag perfect

Fits inside sleeping bag perfect and is super light

Zachary

2023-05-14T20:00:00

Rated 5 out of 5

My fiancé is always cold

My fiancé is always cold when camping. She is cold so often that I started packing two sleeping bags and stuffing them inside each other just for her. It was not the most practical or space saving method so I eventually bought this liner and it solved both problems. Save space and weight because it's so small and adds additional warmth to her bag. The material is very comfortable as well.

Curtis

2023-05-11T20:00:00

Rated 5 out of 5

Small package that packs a punch

This liner is smaller than a soda can which is essential for backpacking. Did not believe this would work at first. Now, I carry it on all cold weather trips. The layer does help keep ya warm! It has also held up well with washes and monthly use.

Jeremy G.

2023-02-04T19:00:00

Rated 4 out of 5

Reactor Extreme Liner

Bought it for my son that is using it for the first time camping this weekend, hence the only 4 star rating. Seems well made and stitched and appears it should work as advertised. Will update this review after he returns.

Jason S.

2023-01-20T19:00:00

Rated 3 out of 5

Haven't used it yet, sorry

Haven't used it yet, sorry busy currently work ing to be able to pay for the next purchase .

Darryl

Sea to Summit Reactor Extreme Sleeping Bag Liner, Standard Specifications

  • Material

    Thermolite Pro & EcoMade Polyester

  • Special

    Bio-based HeiQ Fresh Odor Control

  • Best Use

    Thermal Boost

  • Fits Up To Height

    78" (198cm)

  • Length

    85" (216cm)

  • Dimensions

    85 x 31.5" (216 x 80cm)
    Packed: 5.9 x 3 x 4.7" (15 x 7.5 x 12cm)

  • Weight

    12.8 oz (364g)

  • UPC Code

    9327868158331

About Sea to Summit Reactor Extreme Sleeping Bag Liner, Standard

FEATURED REVIEWS

Worked great

By John A.

I have a down quilt was getting cold drafts coming in and disrupting my sleep. I actually put the quilt inside the liner and I was super warm

Great Warm Liner

By Jachunter

Love that it's easy to pack, light and super warm. The texture is super soft too. Highly recommend as an extra layer for your sleeping bag! Perfect for super cold camping nights.

Enhanced Warmth with Infrared-Absorbing Technology
This Sleeping Bag is an essential addition to any cold-weather sleep system, designed to increase warmth and comfort in extreme conditions. Utilizing Thermolite Pro fabric and hollow-core fibers, this liner features infrared-absorbing ceramic pigments that retain and reflect body heat, delivering a thermal boost to your sleeping bag or sleep mat. Whether used as a standalone layer in milder weather or combined with a sleeping bag for extra insulation, it effectively enhances temperature regulation, keeping you warm and comfortable during cold-weather adventures.

Breathable, Moisture-Wicking & Flexible Design
Made from soft, wicking stretch-knit fabric, this mummy-shaped sleeping bag liner provides exceptional comfort and flexibility while maintaining a snug, heat-retaining fit inside any sleeping bag. The moisture-wicking properties help keep you dry, preventing dampness caused by sweat or condensation. Designed for maximum adaptability, the Reactor Extreme liner conforms to different sleep systems, making it an ideal companion for campers, backpackers, and high-altitude explorers who need both warmth and breathability.

Customizable Ventilation & Long-Lasting Freshness
Equipped with a drawcord footbox and adjustable shoulder openings, this liner provides personalized airflow, allowing you to open or close the ventilation points based on your comfort needs. The footbox is designed to integrate seamlessly with the Free-Flow Zip system in select Sea to Summit sleeping bags, enhancing its versatility. Additionally, the HeiQ Fresh odor control technology keeps the liner fresh for extended use, making it perfect for multi-day treks, winter camping, and long-term expeditions. The drawcord footbox also enables mobility, allowing you to walk around camp while staying warm, making it a practical choice for cold mornings and nighttime use.

Technical Features

HEIQ Fresh
Sea to Summit Liners are treated with HeiQ Fresh FFL, a biocide-free, highly effective odor control technology that uses a bio-based Amino Sugar Polymer to neutralize body odor.

Thermolite Pro
Thermolite Pro has engineered hollow fibers like standard Thermolite but with the addition of permanent ceramic pigments that absorb the body's infrared rays and reflect them back to the wearer.

Thermolite Eco Made
The recycled Thermolite EcoMade fibers are made from 100% textile waste, are GRS-certified, and offer the same quality and durable lightweight warmth as their polymer virgin counterparts but with a lower carbon footprint.

Sea to Summit Reactor Extreme Sleeping Bag Liner, Standard Features

  • Thermolite Pro fabric retains and reflects body heat
  • Infrared-absorbing ceramic pigments boost thermal insulation
  • Stretch-knit fabric provides unrestricted movement and flexibility
  • Moisture-wicking technology keeps you dry in cold conditions
  • Drawcord footbox and shoulder openings allow adjustable ventilation
  • Mummy shape fits all sleeping bags enhancing warmth retention
  • HeiQ Fresh odor control ensures long-lasting freshness
  • Lightweight and compact design makes packing easier
  • Ideal choice in cold-weather camping hiking and mountaineering
  • Seamless integration with Sea to Summit sleeping bags enhances warmth

Warranty Information

This product has a limited lifetime warranty.

Key Features

  • Boost your sleeping bag's warmth with this Reactor Extreme sleeping bag liner.
  • Thermolite fabric adds serious degrees, making it ideal for cold weather camping.
  • Lightweight at just 12.8 oz, this sleeping bag liner won't weigh down your pack.
  • Fits campers up to 6'6" (78 inches), providing ample room inside your sleeping bag.
  • HeiQ Fresh odor control keeps your sleeping bag fresh on extended backpacking trips.
  • Compact pack size (5.9 x 3 x 4.7") saves valuable space in your hiking backpack.

What's in the box:

  • Reactor Extreme Sleeping Bag Liner (Standard)
  • Storage Case