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Therm-a-Rest Hyperion Sleeping Bag: 20F Down

$389.95 - $429.95

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Hyperion Sleeping Bag: 20 Degree Down

Slide the featherlight Therm-a-Rest Hyperion Sleeping Bag: 20 Degree Down into your trusty backpacking pack before a long through hike. The lightweight and packable construction of this sleeping bag will ensure there is plenty of room in your pack for other necessities. The 900-fill Nikwax Hydrophobic Down makes this warmth and packability possible by trapping your body heat in strategic areas and compressing to an impressively small size. As an added bonus the Nikwax treatment means the down can handle moisture without losing its loft so that a surprise rainstorm wont ruin your trip. This bag also features an ergonomic shape and longer zipper that makes it far more comfortable than some competitors bag in the ultralight category.

  • Lightweight and packable bag built to keep you on the move
  • 900-fill Nikwax Hydrophobic Down maintains loft when moist
  • 20° rating keeps you comfortable even when the temperature drops
  • Zoned insulation organizes down to minimize weight, maximize warmth
  • SynergyLink connectors hold your pad in place while you roll over
  • Precise design increases packability to keep your load organized
  • Ergonomic shape and longer zipper boost the comfort of this bag
  • Item #CAS00EO

900 fill Nikwax Hydrophobic Down
Draft Tube
Pad Retainer
SynergyLink Connectors (removable)
European Norm Comfort Rating
European Norm Lower Limit Rating
Storage Sack
Stuff Sack
Claimed Weight
[small] 1lb 3oz [regular] 1lb 4oz [long] 1lb 6oz
Recommended Use
backpacking, mountaineering, weekend camping
Manufacturer Warranty

Tech Specs

California Proposition 65


This product can expose you to chemicals including Toluene, which is known to the State of California to cause birth defects or other reproductive harm. For more information go to

What do you think about this product?


>Rating: 5

Kept me warm

I've used it once or twice and have initial impressions

I used it in late Fall in November when outside temp was about 22F but I was comfortable with only 1 baselayer and 1 fleece jacket. And I love how it light and packed small. Super happy.

>Rating: 5

Extremely Comfortable

This bag is guaranteed to make you feel cozy and warm. It surly handled the three thunderstorms that happened camping! A great bag, from a reliable company.

>Rating: 5

Solid Spring/Summer Bag

I've used it once or twice and have initial impressions

Great for those summer nights when you sleep outside but a blanket just won't do to keep you warm. I was seriously blown away at how toasty this tiny thing got! Didn't need to wear any extra layers to bed when I hit the sack at night. Packs down very small if you are limited on space which is always a plus!

>Rating: 4


I've used it once or twice and have initial impressions

Took this bag spring time camping down in the desert. It kept me comfortably warm but not too hot. The temps dipped into the mid 30's overnight but I slept like a baby. It's a relatively narrow bag and the mummy design makes you feel like you're wrapped in a cocoon, which I like. If you like a little more space in your bag this might not be a good one for you. There are some leashes on the underside of the bag to wrap around your sleeping pad and prevent you from falling off. They will work best with a thermarest pad but can be used on most pads. The bag is super lightweight and comes with a compression sack that makes the bag pack down super small. My one complaint is that the zipper does not zip the whole length of the bag, it only zips about halfway. Sometimes if I'm too hot I like to air my feet out to help cool off. But otherwise seems like a solid bag.