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  • Constructed of insulating Thermolite® fabric, a hollow-core, breathable fiber that provides extraordinary warmth for its weight
  • Adds up to 25°F of warmth to a sleeping bag; can also be used as a summer ultralight sleeping bag
  • Liner helps keep the inside of your bag clean, saving it from the wear and tear of washings
  • Drawcord hood with mini cordlock cinches around face to hold warmth in
  • Mummy shaped liner features a 3D footbox providing plenty of room for feet
  • Comes with a lightweight Ultra-Sil™ stuff sack


View all Sea to Summit Sleeping Bag Liners

REI membership


Best Use Backpacking
Sleeping Bag Shape Mummy
Added Warmth (F) Up to 25 degrees
Added Warmth (C) Up to 14 degrees
Stuff Sack Size 3 x 5 inches
Material(s) Polyester
Dimensions 84 x 36 inches
Weight 14 ounces
Weight - Metric 0.39 kilograms

The REI Difference

100% satisfaction guaranteed

We stand behind everything we sell. If you are not satisfied with your REI purchase, you can return it for a replacement or refund within one year of purchase.

REI's guarantee doesn't cover ordinary wear and tear or damage caused by improper use or accidents.

If your item has a manufacturing defect in its materials or workmanship, you can return it at any time. See our limited warranty.

Gear & advice you can trust

At REI, we live and breathe the outdoors, and we're passionate about sharing our expertise with people of all skill levels. Whether you're new to the outdoors or a seasoned explorer, we'll take the time to understand your needs and help you find the right gear for you.

10% annual member refund

Anyone can shop at REI, but for a one-time $20 fee you can become an REI member and enjoy a lifetime of benefits. These include an annual member refund, typically 10% back on eligible purchases.*



*10% is typical but not guaranteed. Your refund is based on eligible purchases, which exclude REI gift cards, services, fees, REI Adventures trips, REI Garage, and discounted items. Learn more