Sleeping Bags

Therm-a-Rest Mira Sleeping Bag | First Look

Ingenious women's-specific down sleeping bag and mat combo from Therm-a-Rest arrives.


Newly arrived for review is the Therm-a-Rest Mira, a women’s specific, down-filled. sleeping bag from mat-specialist Therm-a-Rest that’s designed to be paired with a NeoAir X-Lite sleeping mat using the brand’s ‘Synergy Link’ straps. That means less filling needed in the base of the bag for reduced weight and bulk. And that’s not all, the bag also features a new reflective ThermaCAPTURE lining to up efficiency further.

First Impressions

There’s loads of stuff going on with the new Mira sleeping bag, effectively a women’s-specific version of the Antares we tried last year, but refined. For starters, the women’s specific cut – it’s narrower around the shoulders and less tapered at the hips – is designed for a closer, more efficient fit for women.

Next, while the bag uses the same zoned construction as the Antares with more down on top, less underneath where it’s compressed, the Mira has much more fill below for added comfort against the surface of the mat.

Synergy Link Connection

And finally, the bag uses stretchy Synergy Link bands to attach it to the mat – we have a NeoAir X-Lite here (374g) but it’ll take any mattress up to 63cm wide – which unlike previous systems, means the mat/bag combo actually works for side sleepers thanks to the stretch in the system. Pocketed mat systems tend to inhibit movement, suiting folk who naturally sleep on their backs.

Finally, the Mira gets a new reflective ThermaCAPTURE reflective film that sits on the inside of the outer fabric of the bag to help reflect warmth back into the bag and increase warmth – women generally tend to seep cooler than men, so it’s a thoughtful addition.

Does the system work? Our Antares test bag saw service in the Himalayas last year and acquitted itself brilliantly, the only question mark being over the slightly crisp-packety NeoAir mat which crackled with movement. The actual Synergy Link system worked really well.

That said the addition of extra full underneath makes a lot of sesnse. You’re still saving weight over a conventional bag, but the extra down underneath simply feels nicer and fills in minor air gaps.

Top Notch

The general quality of the bag feels top-notch. Construction is box-wall to eliminate cold spots, there are proper baffles where you want them at the shoulder and inside the full-length zip. The zip is double-ended so you can vent your toes and more if it’s a tad warm and there’s a nest box foot. There are two lengths available as well, standard and long for further fit optimisation. Oh, and there’s neat valuables pocket up at the head end of things.

Initial Verdict

The Mira has a proper quality look and feel and lots of thought has gone into the design and features and the Synergy Band system works well while reducing overall weight and bulk for a bag of this warmth. On top of that, the women’s-specific cut should give a better fit for many women and by reducing air-gaps, up efficiency further.

In US terms, the bag is dubbed ‘three season’, but for many Brits, the limit of comfort rating of -9˚C should cope with most year-round use if you’re an average sort of sleeper.

All very promising and we wouldn’t be put off by Therm-a-Rest’s relatively recent advent on the sleeping bag front, early signs are that the brand is getting it right. Our mat’s off to the Alps for the next two weeks, so watch this space for a full review coming shortly.

More information

Full details of the entire Therm-a-Rest range of mats and sleeping bags at


  • 853g
  • £330
  • 750+ fill power (US) goose down filling
  • Zoned fill distribution
  • Box-wall construction
  • Synergy Link system mat connection
  • Double-ended zip with baffle
  • Adjustable hood with baffles
  • Women’s-specific design
  • Comfort: -3˚C / Limit of Comfort: -9˚C / Extreme: -28˚C
  • Standard and long options
  • 18cm x 31cm pack size


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