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THERMOLITE Reactor Compact Plus Liner (ADDS up to 20°F)

Sleep warmer, sleep better. Use a Reactor Plus liner.


Size Guide

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The THERMOLITE® Reactor™ Compact sleeping bag liner is the ideal choice for gram counters under 6 feet who want to add warmth to their sleep system. The world’s first ‘hybrid’ sleeping bag liner uses a combination of two weights of THERMOLITE® fabric, with the warmer fabric strategically positioned across the torso and in the footbox. The hollow core THERMOLITE® fibers work like the hollow fur of a polar bear to trap extra insulating air. The Reactor Compact Plus keeps your sleeping bag clean and is super easy to wash. It will bump up the warmth of your sleeping bag considerably, depending on your metabolism, your sleeping bag and sleeping pad, and the environment.

Learn more about which liner is right for you HERE


  • Suitable for use with a rectangular / wide sleeping bag? The knitted fabric of the Reactor is so stretchy that you won’t feel the shape of the liner at all.
  • Useable as a stand-alone sleeping bag in warm weather? Check our blog to learn about conditions where this would work.
  • Equipped with a zipper? The beauty of our sleeping bag liners is their minimal weight and packed size, and a zipper would significantly increase both.

Please note: The packaging of this liner includes the size description ‘Short’. This refers to the 6-foot / 183cm overall length; there is no ‘Regular’ or ‘Long’ Reactor Compact Plus available in North America.



Best Use

Backpacking, Bike Touring, Travel, Camping


Adds up to 20°F to the temperature range of your sleeping bag


Easy to wash and dry. Helps to keep your down or synthetic-insulated sleeping bag cleaner for longer


  • Adds up to 20°F /11°C of warmth to a sleeping bag
  • Lighter weight, more packable than fleece
  • Mummy shape with a box foot
  • Drawcord hood with mini cord lock
  • Packs into its own Ultra-Sil™ stuff sack

Technical Features


The Reactor Series Sleeping bag liners, the Venture, Traverse and Basecamp synthetic Sleeping Bags and the foot boxes of the Women’s Altitude and Journey down Sleeping Bags use hollow core THERMOLITE® fiber to add warmth. These fibers trap extra air for insulation (just like the hollow-cores of polar bear or caribou fur).

In the liners, the knitted THERMOLITE® fabric is soft and stretchy and comes in three different weights: 80g/m² fabric used in the Reactor and the underside of the Compact Plus liners; a 110g/m² fabric which is used in the Extreme, and the core and foot box of the Compact Plus liner; and the Fleece, the warmest of all the fabrics.

THERMOLITE® is also used in the Air Sprung Cell sleeping mats.

Tech Specs

Product Details

Added Warmth
Up to 20°F / 11°C
Best Use
Backpacking, Camping & Winter Camping
Comes With
Ultra-Sil stuff sack
Thermolite polyester fabric
6 ft x 36 in / 183 x 92 cm
5.75 x 4 in / 15 x 11 cm
9.3 oz / 263 g


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