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Sea to Summit Thermolite Reactor Extreme Sleeping Bag Liner (adds up to 14C)

Sea to Summit Thermolite Reactor Extreme Sleeping Bag Liner (adds up to 14C)
$74.96 - $82.46
$99.95 - $109.95
Please select options


The THERMOLITE® Reactor™ Extreme is the warmest backpacking knit sleeping bag liner offered by Sea to Summit. The hollow fiber threads work just like the hollow fur of a polar bear in that they trap heat effectively. When the mercury drops you'll appreciate the mummy shape and drawcord hood with mini cord lock attached. Depending on your environment and sleep conditions, this liner can increase your sleeping bag warmth by up to 14C/25F.

Packed Size Comparison

Similar to a red cup that is solo.


14 oz ˜ Lighter than a roll of paper towels


Adds up to 25°F to the temperature range of your sleeping bag.


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

  • Adds up to 25°F / 14°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
Regular Mummy Long Mummy
Dimensions 82 in / 208 cm 92.5x35.4" / 235x90cm
Stuff Sack Size 6.5x4.5" / 17x11.5 cm 6.5x4.5" / 17x11.5 cm
Weight 14 oz / 399 g 14.9oz / 422g


Sea to Summit THERMOLITE® Reactor Extreme Liner

When the mercury really drops, our THERMOLITE® Reactor™ Extreme sleeping bag liner will seriously extend the warmth, longevity and versatility of your sleeping bag

Part Numbers

Option UPC MPN Store SKU
Regular 9327868022304 REA29651867R
Long 9327868054787 123 SLE55696550