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The Vireo was designed with a single purpose in mind; fast and light alpine climbs where every gram counts. With no hood, no zipper and a variable fill (the lower half is rated at 25ºF / -4ºC, the upper half 45ºF / 7ºC) the Vireo shaves every last ounce. For maximum efficiency and warmth, pair the bag with a down jacket to not only keep you cozy but also minimize extra gear and weight when it matters most.
UL: Ultralight. Pertex® Endurance® 10 denier water-resistant/breathable fabric.
Best Uses: Ultralight Backpacking, Alpinism, Emergency Bivy
Details
- No zipper to conserve weight and bulk
- Drawcord on open end to cinch off apertures
- Designed to be worn with a down jacket for upper-body warmth
- Differential fills - lower half is filled to 25ºF / -4ºC while the top half is filled to 45ºF / 7ºC
- Stuff sack and cotton storage bag included
Additional Info
Interior Length |
68" 68" / 173 cm 74" 74" / 188 cm |
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Dimensions | 66" shoulder / 48" hip / 38" footbox |
Zipper | None |
Shell | Pertex® Endurance UL |
Lining | Flite 15 denier ripstop nylon |
Fill Power | 950+ Goose Down |
Origin | Made in Seattle, USA of imported materials |
Temp Rating | 25ºF (-4ºC) / 45ºF (7ºC) |
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Fill Weight |
68" 8.7 oz / 247 g 74" 9.4 oz / 267 g |
Average Weight |
68" 15.6 oz / 441 g 74" 1 lb 0.7 oz / 474 g |
Packed Size | 5L |
Reviews
- Reviews
- Questions

Perfect for Fast/Light Travel
Used this when knocking out the Huayhuash Circuit with some alpine variations in 6 days. For a solo, unsupported high altitude trek, weight was of the utmost importance. I used this bag with RaidLight Ultra MP+ pants, Superior Fleece Brule, Squamish Hoody, and my FF Eos down jacket each night on top of an XTherm pad and was never cold. Temps were below freezing at pretty much every campsite (to be expected at 15k' near glaciers). I run a little warm so your mileage may vary. For 15oz though, I don't think this bag can be beat. I intend to use it on all my future summer climbs in the Cascades, lower altitude in AK, etc. It compresses tiny, so I was able to have 6 days of supplies and my shelter and everything in a 38 liter pack, furthering the weight savings. Pretty killer. I'd buy a winter version of this instantly, I.e., something designed to be paired with a 6000m parka. Such an efficient system.

This is it
I have it paired w a 900 fill jacket from a competitor and it’s perfect for intended ultra light use. Was really happy with this as my sleeping system for summer alpinism in the Bugs, BC Rockies and Cascades.
Almost Perfect
As others have commented, the Vireo is great for its intended use. Great shell fabrics and the quality construction you expect from FF. At 6'3" 190# broad shoulders I am impressed how comfortable this bag is, enough room for a big puff on cold nights and plenty of length in the 74" bag. Impressive considering how light and packable it is. The differential fill is subtle but noticeable. Mine came with a size 6 stuff sack which seems too big for this ultra compact bag. I recommend a size 5 be included instead. Lastly and most important, please offer Hydrophobic down for this bag! The design intent is to wear clothing for additional insulation in this bag. In use this brings moisture inside. Snow, rain or sweat yields wet clothing which must be dried, along with gloves or boot liners. Managing moisture and drying gear is critical for multi-day alpine outings. Hydrophobic down would manage this moisture and function better for this designed use. Offering the Vireo with Hydrophobic down would make it perfect. If you agree let FF customer service know.
Perfect for intended use
A remarkably light, comfortable, warm, and innovative bag. I was hesitant about purchasing the Vireo UL instead of a more versatile quilt like the Flicker UL, but was pleasantly surprised after using this bag for two weeks on the PCT in Northern Washington. I ended up sleeping half-outside the bag in temps above 45F, so I'd look elsewhere if you'll routinely be in warm conditions. That said, the scant weight is almost unbelievable since it meets, if not exceeds, its temperature rating. Paired with an Eos jacket, silk base layer, and thin wool socks, this bag provides warmth on par with my 15+ year old Swallow 20F degree bag at less than half the weight. It's worth noting that without a zipper to block the passage of down, the baffles are truly continuous all around the bag: you can move down beneath you in warmer temps and above you in cold weather, assuming you have a warm enough pad. Curious to see how late in the season I can take the Vireo UL into the Sierra with heavier base layers " and perhaps a Hooded Helios in the future!
The perfect lightweight bag
Bought this for an ultralight trip. Compacted great and kept me plenty warm during summer nights at altitude. Will be using it for many more activities!