Feathered Friends Vireo UL Review

For bringing only the absolute essentials on fast and light trips, the Vireo UL is a standout bag. Without a hood, a side zipper, and very few other accoutrements, save for a simple cinch at the head end to help prevent drafts, the Vireo UL is essentially a down-insulated tube. High-quality materials, including 950+ fill power down, further optimize its impressive weight-to-warmth ratio. It's a specialty bag, but the Vireo UL is perfect for alpine outings where both weight and packed volume are at a premium.

Warmth

The Feathered Friends Vireo UL has a differential down fill – the top half of the bag has less insulation than the bottom half. Because of this unique design, overall warmth is a little harder to describe than with other, more traditional sleeping bags.

The ratings are conservative, with a Comfort rating for the bottom of 25°F and the top of 45°F. Both are set by the manufacturer, rather than by independent testing. As designed, you'll want to bring along an insulated jacket with a hood to supplement warmth, bringing the entire bag up to a 25°F Comfort rating. We carried a down jacket with approximately 4-7 ounces of quality down, and felt that, with that, the Vireo UL closely compared to other 25°F Comfort-rated bags we tested.

The Vireo UL's sewn-through, wide, and horizontal baffles allow the down fill to loft highly. Sewn-through designs have a reputation for creating cold spots where the baffles meet, but we didn't experience any problems, even when temperatures tipped toward freezing while camped at 10,000 feet in Colorado's Indian Peaks Wilderness.

Weight

Compared to other ultralight sleeping bags around its temperature rating, the weight of the Vireo UL is truly exceptional. We tested the Long, 74" version, and the bag alone weighs only 16.1 ounces (456 grams). Add 0.7 ounces (20 grams) to the total weight for the included 5-liter stuff sack.

Featured Friends uses 950+ fill inside the Vireo UL, which lofts up to higher volume and packs down tighter than lower-rated fill. There are approximately 267 grams of down fill in the 74" version we tested and 247 grams in the 68" length. Sewn-through baffles are used to further optimize packability and overall weight savings, as they use less fabric than box baffles. There's not much else to the Vireo UL, save a single simple cinch at the head end to help vanquish drafts.

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Taking advantage of a jacket you're already bringing is how the Vireo UL really saves weight. This clever solution is most likely to appeal to self-powered travelers like fast-and-light mountaineers, super-ultralight backpackers, and FKT chasers, rather than your average ultralight backpacker.

Comfort

The Vireo UL is dreamy to snooze in, mainly because the light, airy down inside the generously sized baffles lofts up. The lightweight liner fabric feels silky smooth against our skin, and with no metal zippers or cinches, there is nothing to catch on our clothing. Without a hood or any of these accessories, there is no “bottom” or “top” to the bag, which may appeal to active sleepers that toss around at night.

Our 5' 11" tester was somewhat between the regular 68" length and the longer, 74" length. In the end, we chose the 74" to test, and were happy with our decision because of the low cut of the shoulders. Make sure you're measuring from your feet to the bottom of your chin, as that is what the bag is designed to cover. Adding a little extra length makes it easier to stash gear inside the bag, like water and electronics, to keep them warm.

We are not immune to feeling claustrophobic. Thankfully, the Vireo UL's shoulder circumference is on the generous side at 65", similar more to quilts we've tested than tighter sleeping bags. This measurement actually increases to 66" at the elbow, then constricts down to 52" at the hip, and 40.5" at the footbox.

Versatility

Due to its unique design, the Vireo UL simply isn't as versatile as other sleeping bags we tested. Instead, you'll need to carefully plan and work within the constraints of this specialty piece of gear. At a minimum, you'll need to plan to carry an insulated jacket with a hood (or a warm hat) to ensure a comfortable night's sleep.

No side zipper of any sort means there is no way to either quickly unzip to release heat or fully unzip and use the bag as a makeshift blanket. As a result, the Vireo UL works best when temperatures are close to the advertised 25°F Comfort rating, unlike other bags with zippers, which allow for a comfortable night's sleep over a wider temperature range.

We had our reservations about the differential fill and how it would feel as temperatures shifted during the night. We often started out with an insulated jacket, and when we got too warm, we just took it off. If we needed a little more warmth, we draped the jacket over us. All the while our lower legs and toes were comfortable without overheating.

Features

Maybe the Vireo UL's strength lies not in the features it packs, but in what it leaves out to save both weight and packed volume. Unlike the majority of sleeping bags we've tested, this one doesn't have a side zipper or a hood – but it is still a sleeping bag, and not a quilt.

The shell is a wispy, 7D Pertex Quantum Pro reinforced with 30D ripstop threads. The lining is an ever-so-slightly heavier-threaded 10D Flyte recycled nylon for most of the interior, alongside a tougher 15D Pertex Diamond Fuse fabric in the footbox. By choosing specific fabric weights for specific sections, this bag has enough durability where it's needed, while squeezing out even more marginal weight savings.

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If all of these design choices seem very extreme, you are right. The Vireo UL is designed to offer only the bare minimum in a sleeping bag. One consolation is a simple cinch that helps seal the head end of the bag. Otherwise, there are essentially no “features” to speak of – it's the materials and construction that are interesting.

Should You Buy the Feathered Friends Vireo UL?

The Vireo UL keeps things as simple as possible, dropping all unnecessary components to deliver an absolutely uncompromising yet comfortable ultralight sleeping bag. We almost always pack an insulated, hooded jacket, so the clever differential fill makes sense – you're taking down from your sleeping bag, and putting that weight in another, more versatile piece of gear. If your goal is to drop as much weight as possible, then the Vireo UL is a great way to do so. However, we wouldn't recommend this bag to more casual ultralight backpackers; it's simply too specialized.

What Other Ultralight Sleeping Bags Should You Consider?