Sea to Summit

Sea to Summit Reactor Insulated Sleeping Bag Liner

$55.96
sizeS

65+ bought in the past month

About this item

  • thermolite
  • Imported
  • Insulated sleeping bag liner adds extra warmth and personal hygiene to any sleeping bag.
  • Thermolite Pro technology using knitted, hollow-core fibers and absorbing infrared ceramic pigments to reflect your body's heat back to the wearer for enhanced warmth and comfort
  • Drawcord footbox can be opened or closed for optimal comfort and integrates perfectly with the footbox of our Free-Flow Zip system in select Sea to Summit sleeping bags
  • HeiQ Fresh odor control technology helps keep the liner fresh even after extended use
  • Knitted fabric provides incredible stretch and freedom of movement in this mummy-shaped liner and works seamlessly with sleeping bags of any shape, Sea to Summit Guarantee is offered for the Lifetime of this product
$55.96

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Product details
BrandSea to Summit
Occupancy1 Person
ShapeMummy
Seasons3 Seasons, Spring
Temperature RatingDesigned for temperatures down to 25 degrees Fahrenheit below user's comfort range
Age Range (Description)Adult
SportMountaineering, Climbing, Backpacking, Hiking
Materialthermolite
Fill MaterialThermolite hollow-core fibers
Closure TypeDrawstring
Technical specifications
brandSea to Summit
occupancy1 Person
shapeMummy
seasons3 Seasons, Spring
temperature_ratingDesigned for temperatures down to 25 degrees Fahrenheit below user's comfort range
age_range_descriptionAdult
sportMountaineering, Climbing, Backpacking, Hiking
materialthermolite
fill_materialThermolite hollow-core fibers
closure_typeDrawstring
item_weight12.96 ounces
outer_materialthermolite
fabric_typethermolite
size78 x 31.5
maximum_height_recommendation7 Feet
global_trade_identification_number09327868158317
item_package_dimensions_l_x_w_x_h8.5 x 4.8 x 3.86 inches
package_weight0.37 Kilograms
item_dimensions_lxwxh85 x 31.5 x 3 inches
brand_nameSea to Summit
country_of_originChina
suggested_usersunisex, all ages
manufacturerSea to Summit
part_numberSS42100
styleExtreme Compact (78 X 31.5)
fill_material_typeThermolite hollow-core fibers
best_sellers_rank#14,720 in Sports & Outdoors ( See Top 100 in Sports & Outdoors ) #6 in Camping Sleeping Bag Liners
date_first_availableJanuary 24, 2024

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Customer reviews

4.7250 ratings
  1. 588%
  2. 413%
  3. 30%
  4. 20%
  5. 10%

Customers say

Customers find the sleeping bag liner keeps them warm, with one mentioning it can be closed with a drawstring for maximum warmth, and another noting it works well as a leg warmer.

★★★★★

Warm and comfortable.

JKFebruary 10, 2026✓ Verified purchase

Kept me pretty warm with my 32F down sleeping bag in 25F weather. My feet got a little cold but wasn’t bad enough to keep me up all night. Read more

★★★★★

Great liner for summer months

Cindy WalkerJanuary 7, 2026✓ Verified purchase

i’m not keeping this because I need something a little warmer. I’m getting ready to start the Appalachian Trail and I just don’t think this is warm enough for me looking for a warmer insulated liner for my sleeping bag. If I wouldn’t be hiking in the cold, I probably would’ve kept it. Read more

★★★★★

It worked for me!

Wm. Chad SkeltonJanuary 29, 2026✓ Verified purchase

First night was in the 20’s f and worked great with my sleep system. I woke up to a small amount of snow and was warm without feeling drafts in my hammock. I use this every time in my sleep system Read more

★★★★★

Works great

Cruis46January 14, 2026✓ Verified purchase

Works great. My bag went from adequate to comfortable, with minimal weight added to my pack. Read more

★★★★☆

Sleeping bag liner.

Brad K.December 29, 2024✓ Verified purchase

This bag liner is nice and warm. Drawstring bottom is great for sitting around the fire and keeping your legs warm. The snaps and hood helps keeps wrapped around you while you roll around at night. Was out for a cold evening and usually sleep in my puffy. Ended up taking it off in the middle of the night cause the liner was keeping me extra warm. Read more

★★★★★

Very warm, easy to get in and out of

Jon C.November 30, 2025✓ Verified purchase

I used this for several nights in 30 degree temps as a liner in my hammock, combined with a 20 degree top and under quilt. With just the 20 degree quilts I would have been way too cold with the wind chill. However this liner provided more than enough extra insulation for the conditions. Also, the easy close foot box made it very convenient to get in and out of, especially with the added difficulty of hammock camping. Read more

★★★★★

Versatile and effective both as a warmth-increasing line and as a standalone bag

J. T. GotsickJune 28, 2025✓ Verified purchase

I bought this to store in my camper as a 'just in case' item or spare, and have been very pleased with it. It definitely adds warmth to a main sleeping bag without making one feel clammy inside, and it works nicely as a light bag on warmer nights. The open footbox adds further versatility (you can close it with a drawstring for maximum warmth) too. If you're through-hiking the AT, it's too bulky and heavy to justify taking along, but if you do RV camping or are going out for one or two nights and expect variable weather, this is a very worthwhile addition to your kit. Read more

★★★★★

Sleeping bag liner.

wayne raberDecember 12, 2025✓ Verified purchase

Very happy with this quality liner. Definitely worth buying Read more

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