For years I have avoided winter camping, assuming that it would be impossible to stay warm, be comfortable, and get a good night’s sleep. However, after testing the Therm-A-Rest Altair sleeping bag paired with the Therm-A-Rest NeoAir XTherm mattress I have discovered that it is possible to sleep well and stay warm even in cold temperatures.

Therm-A-Rest 3_1

This year Therm-A-Rest released a new technology which integrates their sleeping bags with their mattresses, with a unique link system. According to Doug Jacot, Vice President of Therm-A-Rest, over two years of research went into development and design of the Synergy Link Connector system. The system essentially links the sleeping bag with the mattress but in a way that still allows for movement inside of the sleeping bag, providing a comfortable sleep experience.




  • The Altair sleeping bag is cut for comfort, making it roomier in the shoulders and hips. This makes it easy to change positions without compromising warmth, especially if you sleep on your side. Additionally, the Synergy Link mattress connectors keep the mattress firmly on the ground providing a layer of insulation no matter how much tossing and turning occurs inside of the sleeping bag.
  • This sleeping bag/mattress combination is incredibly warm. The XTherm mattress has an R-value of 5.7 and is made of reflective material which acts as insulator to trap and recycle body heat. The Altair sleeping bag has an EN comfort of -5 C/24F, meaning that the average woman can comfortably sleep in this bag at temperatures in the low 20˚ temp. Unlike most sleeping bags, there is more insulation on the top of the bag than the bottom allowing the mattress and sleeping bag to work together to maximize warmth without unnecessary bulk.
  • The XTherm mattress and Altair sleeping bag have a combined weight of three pounds, two ounces (regular size). Since the system is so light it is perfect for a backcountry skiing or a snowshoe trek. Both the sleeping bag and mattress pack up small. The mattress, when deflated and packed is just larger than a 1-liter water bottle.
  • The SynergyLink system is designed in such a way that the sleeping bag is interchangeable with other mattresses. In warmer temperatures the sleeping bag can be paired with a mattress with a lower R-value making it a versatile piece of gear.
  • While it is easy to get caught up in the big features that make this sleep system great, there are several other things like two and a half inches of mattress, goose down, and a zippered pocket to stash small items on the side of the sleeping bag, which further enhance the product.

XTherm Mattress_1


  • The Neo Air XTherm mattress feels flimsy and is a bit noisy. Therm-A-Rest puts their products through rigorous testing, but I am anxious to see if the material is durable enough to withstand years of use.


The Therm-A-Rest Altair Sleeping Bag combined with the Therm-A-Rest NeoAir XTherm  Mattress through the Synergy Link system provides unbeatable comfort and warmth while still being lightweight and packable. Therm-A-Rest did not miss a single feature when they designed this product.


Tech Specs

Manufacturer: Therm-A-Rest

Altair 0F\-18C Down (Regular)

Color                    Blue

Weight                 2 lbs 7 oz/1120g

Price                     $459.95

Website                Cascade Designs Altair 0

Date Available   Currently Available

Fits                        6 ft/183 cm

Girth, Shoulder  62 in/158 cm

Girth, Hip            58 in/147 cm

Girth, Foot Box  40 in/102 cm

Packed Dim.       8×18 in/15 Liters

EN Comfort         -5C/24 F

Fill                         750 Goose Down

Zipper Side          Left

NeoAir XTherm (Regular)

Color                    Reflex Gray

Price                     $189.95

Website                Cascade Designs Neoair XTherm

Date Available   Currently Available

R-Value               5.7

Weight                 15 oz/430 grams

Width                   20 in/51cm

Length                 72 in/183 cm

Thickness           2.5 in/6.3 cm

Packed Dim.      9×4.0/23×10

Warranty information: Therm-A-Rest takes pride in offering the highest-quality outdoor sleep gear, and we stand behind everything we make. If you experience a problem with any Therm-A-Rest® product, we will do everything we can to repair or replace it as quickly as possible.

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