Reactor Extreme Sleeping Bag Liner


SKU: 301571

Innovative infrared technology provides exceptional warmth in colder-weather

An essential component in your sleep system, the Reactor Extreme liner with Thermolite® Pro fabric utilises innovative infra red-absorbing ceramic pigments to give your system the thermal boost needed in colder-weather adventures.

The soft, wicking stretch-knit fabric provides unmatched comfort and freedom of movement while still allowing the Reactor Extreme liner to fit any sleeping bag. Additionally, the drawcord footbox offers plenty of ventilation and the versatility of walking around camp while still wearing your liner if needed.

Thermal Boost

WEIGHT: 12.6oz | 342g

LENGTH: 78in | 198cm

PACKED SIZE: 5.9 x 3.0 x 4.7in | 15 x 7.5 x 12cm


  • Thermal boost to retain heat and warmth. As the core of your sleep system the Reactor liner extends the performance of your sleeping bag and sleeping mat in the coldest of conditions
  • Thermolite® Pro technology using knitted, hollow-core fibres and infrared-absorbing ceramic pigments to reflect your body's heat back for enhanced warmth and comfort
  • Drawcord footbox and shoulder openings 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 odour 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 perfectly with sleeping bags of any shape
  • Sea to Summit Guarantee is offered for the Lifetime of this product

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.

Tech Specs

Comes With
Storage Case


Thermolite® Pro & EcoMade Polyester


Bio-based HeiQ Fresh Odor Control

Compact Standard
Dimensions 198 x 80 216 x 80 cm
Packed Size 15 x 7.5 x 12 cm 15 x 7.5 x 12
Weight 342g 364g


Does the Reactor Extreme liner have a zipper?
No - to keep weight and packed volume down, we did not include a side zipper. Snaps at the shoulders mean a wider opening than some liners for entry and exit (and the drawcord footbox allows you to vent your feet or hitch up the liner and walk around camp)

Can the Reactor Extreme liner be machine washed?
Yes. It can be washed in a machine with normal supermarket detergent - but avoid fabric softeners which reduce wicking performance. Machine dry on a cool/low setting (no dryer sheets) or air dry

How much warmth does a Reactor Extreme add to a sleeping bag?
This depends on how well your sleeping bag retains warmth (not the same as its temperature rating), how well your pad insulates (not the same as its R-Value) and a lot of other factors. You should see a fairly solid boost if the liner is used with an appropriate sleeping bag and pad. 

Spicy orange

Customer Reviews

Be the first to write a review