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You're not afraid of a little frost.

Whether you're hitting the mountains for a weekend or the European Alps for a season, the weather-resistant Sea To Summit Trek TkIII 12 Degree Down Sleeping Bag gives you room and warmth enough for comfy, restful nights. Stuffed with the wonder-feather Ultra-Dry Down 650+ that stays lofty and dry, a draft tube, and a dual-adjustable hood, you'll stay cozy even when temps dip below freezing. And you won't have to sleep still like a wrapped-up mummy; the tapered rectangular shape allows your feet to fall open so your eyelids can close.

  • Comfy in three seasons weather, with a 12F lower EN rating and 23F comfort rating, you’ll stay cozy even when the temps plummet and your water bottle ices over
  • The 650-fill down gives you superior loft and insulation for a better warmth-to-weight ratio than anything on the planet
  • Differential-cut tapered rectangular shell with 3D side walls, 60/40 fill-ratio, and side block baffle gives wiggle room with lean-fit warmth
  • Regular length comfortably accommodates a person six feet tall; long length fits someone six-foot-eight
  • Breathable, downproof 2D Perma Shell 33D nylon weave with DWR finish repels water at its durable exterior and condensation on the inside to keep you dry
  • Super-soft, downproof lining breathes and feels luxurious next to skin for all-night comfort
  • Cushioned internal hood drawcord with dual adjustment hugs your head with downy warmth
  • Two-way zips with separate foot zip let you convert bag to duvet for indoor or warm-weather use
  • Zip draft tube with anti-snag seals out the cold for optimal cozy comfort
  • Weighs a mere 2lb 11oz (regular) or 2lb 13oz (long) for easy portability
  • Compresses in bag from 15 liters to 5 liters, so you’ll have room in your pack for other things
  • Oversized internal zippered pocket secures traveling essentials at your side
  • Includes Ultra-Sil compression stuff sack, mesh storage bag, and laundry bag for easy maintenance and convenience

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Here's what others have to say...

What are the dimensions and weight of the SHORT version?


For the Short, here are the specs:

Make Height (Short): 5'5''

Dimensions (Short): 58, 57, 38 in (chest, hip and foot)

Weight (Short): 2 lb 11 oz / 1215g

Shoot me an email anytime you have questions!

Jared D.

Expert Gearhead


Unanswered Question

Can I linked together two sleeping bag (one with R zipper and one with L)?



  • Familiarity:I've used it several times

One of the best sleeping bags I have ever used! I purchased it for a motorcycle road trip and this light compact sleeping bag was perfect for the lack of space I had for packing things on my bike. The sleeping bag kept me warm on the cold nights and the easy open zippers on the inside of the sleeping back allowed me to keep it well ventilated on the warmer nights. Very happy with this purchase!

I'm 6'0" tall. Should i go with the regular that is 6'0" or would it be too tight. Should i be looking at stepping up to the long?

I would step it up to a long so you are comfortable and can put some odds and ends in the sleeping bag should you need to dry them out.

You can call or email me directly. 801-736-6398, or

Unanswered Question

would this fit into my terra 45 sleeping...

would this fit into my terra 45 sleeping bag compartment?


First Impressions

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

Ok - just received this sleeping bag today. My first impressions are - Wow - This is slick. The bag came in an oxygen-sealed plastic ziplock-style bag, and then within that is a mesh zip-up duffle. Within the duffle is the bag itself, a laundry bag and a sts compression bag.

It is also accompanied by a letter describing the bag and the down within it, as well as a Final Test Report/Content Analysis on the down within it. They also include a 'slick' spec sheet outlining all details of the bag. I've compressed the bag within the provided compression bag and its the size of a basketball without really tearing down on the straps. I was hoping it would be a pinch smaller but all in all not bad.

Getting into the bag itself - it's really comfortable, with lots of leg/foot room (I'm about 5'11'' with claustrophobia issues). With my arms 'tucked' in, it's tighter than extra-wide bags I'm used to, but still not bad. And I typically end up sleeping with my arms outside of the bag anyway.

I'm planning on taking this on the West Coast Trail in early summer so I wanted something lightweight, with 'dry-down' that is compressible, but not confining. So I think this will fit the bill.

On top of this, Backcountry was able to pricematch the bag dropping the cost by about 25% so that was a great bonus.

I will add further thoughts after I try it out in the field.

First Impressions

what is the difference between a DWR...

what is the difference between a DWR coating, and a DWR Finish?

The TKII has the 'Coating' while this has the 'Finish'

also - are you getting the TKII in regular and long sizes?


Hey Strongbow,

Nothing really, the coating is put on the fabric in the factory and it results in a finish. Either one is water repellant and will have to be replenished. Hope this helps.


Sea to Summit Review

  • Gender:Female

If you want more information on this bag, check out this link: