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Sea to Summit Thermolite® Reactor Fleece Liner (Adds up to 32°F)

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  • Regular price $ 99.99

The THERMOLITE® Reactor™ Fleece liner is Sea to Summit’s warmest sleeping bag liner. Add one to your sleeping bag before heading into really cold environments  or, use as a 'stand alone' sleeping bag when the weather is warmer. The hollow core THERMOLITE® fibers have the same hollow structure as polar bear – when made into a fleece, this traps a lot of insulating air. Luxuriously soft, the Reactor Fleece is perfect as part of a cold weather sleep system – plus it will help keep your sleeping bag clean.


The Reactor Fleece is Perfect For...

  • Backpackers looking to add warmth to their sleeping bag for winter camping
  • Warm-weather campers who don’t need a full sleeping bag
  • Paddlers or desert users who want an easy-care summer sleeping bag they can easily wash the sand out of
  • Backpackers looking to extend the performance of a (perhaps older) sleeping bag for winter camping

Other Liner Options

  • The Reactor Extreme Liner is a slightly more compact, slightly lower-priced alternative for more moderate temperatures.


  • Thermolite® fleece fabric is incredibly comfortable
  • Technical mummy shape with drawstring hood
  • Quarter zip makes it easy to get in and out
  • Easy care – machine wash; no special soap is needed. Avoid fabric softeners & dryer sheets to maintain wicking performance
  • Ideal for use as a sleeping bag in warmer weather or sandy environments
  • Significantly improves the thermal performance of your sleeping bag
  • Packs into its own Ultra-Sil™ stuff sack


Easy to wash and helps to keep your down bag cleaner for longer.