The Therm-A-Rest Vesper 20F represents another step in a growing trend: mainstream gear companies increasingly catering to the ultra-light crowd (the REI Magma Trail Quilt 30, which we’ll compare to the Vesper to later in this article, is another example of this phenomenon). The Vesper is EN/ISO safety rated for a range around 20 F (-6.7 C) with a comfort rating of 32 F (0 C). Premium materials and a no-frills but elegant design combine to form a 19 oz (539 g) down quilt that packs down small, making the Vesper a powerful tool in an ultralight sleep system.
Features and Specifications
- Differential cut enclosed footbox
- DWR treated shell
- Horizontal baffle orientation
- Perimeter side baffles to minimize down migration
- Insulated, adjustable collar with snap closure
- Box-sewn baffles
- SynergyLink™ sleeping pad connection system
- Nikwax Hydrophobic Down™
- RDS certified down
- Four-point-compression stuff sack included
- Made in China
Specifications (size regular)
- Weight: 19 oz (539 g)
- Temperature Rating*: 20 F (-6 C)
- Fill Type: 900 fill Nikwax Hydrophobic Down
- Fill Weight: 12 oz (340 g)
- Loft Height: 4.5 in (11.4 cm)
- Dimensions: 75 x 58 in (191 x 147 cm)
- Compressed Dimensions: 8 x 5.5 in (20 x 14 cm)
- Shell Fabric: 10D Nylon RipStop (DWR treated)
- Lining Fabric: 10D Nylon RipStop
- MSRP: $379.95
*More on this in the Temperature Rating and Warmth section
I’ve logged more than 2,000 trail miles and nearly 200 nights in quilts of various makes and models, so I know what I like in a quilt. To me, the ideal quilt should sit at the sweet spot of minimalist design and functionality. A quilt plagued by cold spots, drafts, or lack of coverage doesn’t do anyone any favors no matter how light it is. Similarly, a quilt that has too much material or too many extra features might as well be a mummy bag.
A good quilt needs to allow for more temperature control than a mummy bag while still remaining firmly affixed to a sleeping pad. It needs to shave ounces by utilizing the most minimal amount of fabric possible while still being wide and long enough to provide coverage for a side sleeper. A well-designed quilt should retain its loft over a long period of time, be as breathable as possible while still being water and moisture resistant, and be sewn and baffled in such a way as to minimize cold spots and down migration.
Some companies design quilts to be multi-functional; manufacturing quilts that can be opened completely like blankets – allowing for more flexible temperature regulation, decreased drying time when laid flat in the sun, or even worn around camp as a poncho. These are nice features but only one of them is extremely practical: having the capacity to lay a quilt out completely flat in a patch of sunlight is massively useful in the event of a catastrophic soak, or even a run of humid nights.
As for temperature control, I personally haven’t found blanket-style footboxes to be any more efficacious than simply adjusting my head insulation or rearranging the upper part of the quilt. I’ll discuss footbox styles (and why I believe Therm-A-Rest’s approach to the Vesper to be the best option) in greater detail later in this article.
I spent many of my outdoor nights sleeping in a quilt that was designed to be used as a poncho on chilly mornings (in fact that feature was one of the reasons I bought that quilt). I quickly learned that four inches of loft is a cumbersome thing to wrap around yourself while doing camp chores or, more terrifying, cooking over the unregulated flame of an alcohol stove. So I’m fine with quilt designs focusing on functionality rather than bells and whistles.
Description of Field Testing
The Vesper was my companion on every extended and short-term trip I took between July 2018 and April 2019. I spent upwards of 30 nights in the Vesper across three alpine seasons, including while at altitude, in four different shelters, and with three different sleeping pads. In short: optimal conditions for quilt testing!
A summer trip to Wyoming’s Wind River Range provided ample opportunity to put the Vesper’s DWR treatment and hydrophobic down through their paces. I followed that up with a ten-day trek through the Absaroka-Beartooth Wilderness in Montana – where nighttime winds were gusty and high-altitude early fall-temperatures dropped into the low thirties.
Finally, I took the Vesper out on several multi-day late fall / winter / early spring excursions in the eastern Sierra Nevada. Overnight temperatures on these occasions sometimes dropped into the teens, and were on average closer to the mid-twenties.
My base layers were mostly Brynje wool thermo mesh t-shirt, leggings, and beanie with thick Darn Tough wool socks. Occasionally I used an Icebreaker merino wool t-shirt and Smartwool leggings.
My performance assessment of the Therm-A-Rest Vesper 20F will consist of the following considerations:
- Pad Connection
- Temperature Rating and Warmth
- Cut, Design, and Special Features
At this point, it should come as no surprise that high-end quilt and bag manufacturers are using silky, lightweight fabrics for both shell and lining. The Vesper is no exception. Therma-A-Rest utilizes a featherweight 10D Nylon RipStop fabric on both the shell and lining of the Vesper, and the result is a quilt that is a tactile pleasure to sleep in. The fabric is quiet, soft, and so thin as to be translucent in direct sunlight. The upshot is you can easily find and mitigate clumps of down if necessary, although that isn’t much of a problem with the Vesper’s baffle design.
The shell is treated with DWR, and it easily shed the mist and splashes I encountered during several intense rainstorms in the Winds. Likewise, a quick shake in the morning flung away the cold-weather condensation that collected on the surface of the quilt in the eastern Sierra Nevada. I never felt clammy, stuffy, or drafty while sleeping in this quilt – so my judgment is that Therm-A-Rest managed to balance breathability and wind/water resistance in its choice of fabric. I certainly didn’t notice any rips, tears, or runs in the fabric after sustained use, so it seems to be sturdy enough. I’d be careful with it though.
If I had one fabric gripe, it would be this: I’m a fan of dark colored fabrics on the interior of my bags to aid drying on longer trips (full disclosure: I have no measurable evidence that a black or dark fabric dries faster than light fabrics in direct sunlight. Anecdotally though … yes). By contrast, the Vesper is a light grey. This color choice also tends to show stains and smudges.
Therm-A-Rest stuffs the Vesper with 12 oz (340 g) of 900-fill Nikwax Hydrophobic RDS certified goose down. This is premium stuff (most quilts come standard at 800 or 850 fill) and likely accounts for a good chunk of the Vesper’s $379.95 price tag. The payoff is a quilt that compresses extremely well but lofts up to a thickness of around 4.5 in (11.4 cm) and boasts an impressive warmth-to-weight ratio.
“Vertical or horizontal?” – this is the eternal question. In my experience, vertical baffles mitigate the down migration that can happen over a long period of sustained use. Vertical or hybrid (horizontal on the chest and vertical on the legs) baffles are now quite common in both quilts and sleeping bags. Therm-A-Rest goes old school with the Vesper and uses a horizontal baffle system – with a twist. The horizontal baffles extend about halfway down the sides of the bag. From there, a smaller series of perimeter side baffles takes over.
Horizontal baffles were my chief concern with the Vesper’s design: I have several quilts with horizontal baffles, and all suffer from cold spots in the baffles at the head end because of down migration into the sides of the baffles. So far, Therm-A-Rest’s use of perimeter baffles seems to be working: I haven’t experienced any noticeable down migration or cold spots using the Vesper, despite the side baffles seeming slightly under-filled. Holding the Vesper up to the light reveals areas in the side baffles that seem altogether lacking in insulation. Again, I haven’t noticed any side drafts in the Vesper, so this is likely an extremely precise weight and design consideration. However, if you are the kind of person for whom the phrase “twenty percent overstuffed” holds great importance, the low fill volume in the side baffles is likely to bother you.
The horizontal baffles are 5.5 in (13.9 cm) wide. All the baffles in the quilt are box-sewn, meaning there are thin layers of mesh between the seams to prevent down migration between the chambers. This contrasts to a sewn-through style, where the liner and shell are sewn together to create a barrier. Sewn-through can create cold spots but is lighter, where as box-sewn adds material (i.e. weight) but avoids creating points of zero insulation.
I’m happy that Therm-A-Rest went with a box baffle system in the Vesper. I wonder how many ounces they could have dropped with a sewn-through design, but they were already down to 19 oz (538.6 g) so they probably figured that they had some wiggle room. Ultimately I feel it’s the right choice. As I’ve already said, the Vesper is remarkably draft free and warm. Box baffles certainly play a part in that.
Cascade Designs (parent company of Therm-A-Rest) has a well-deserved reputation for tightly constructed products. The Vesper meets these standards … for the most part. I’d say that 99% of the seams and stitching are tight, even, and well-sewn. It’s perhaps unfortunate timing that after thirty nights of use I noticed the first loose threads (only two of them) while photographing the Vesper for this review.
The extremely thin 10D Nylon probably doesn’t help either – as the thin, light fabric may not hold stitching as well as heavier fabrics. I reached out to Therm-A-Rest about this issue and was told that my sample Vesper was produced on a different manufacturing line than the consumer products which were produced later. Small manufacturing flaws are not uncommon in such cases as, according to Therm-A-Rest, “sometimes we see slightly less quality control with the sample line.” Our experience here at Backpacking Light backs this up, so we are considering the loose threads on this sample Vesper to be a non-issue.
It will be interesting to see how the stitching holds up over even longer sustained use: I plan on using the Vesper on upcoming thru-hikes of the Tahoe Rim Trail and Arizona Trail at minimum.
Sleeping Pad Connection
Out of all the design elements found in quilts, perhaps nothing has as much variation as sleeping pad connection systems. Hooks, buckles, straps, cords: everybody seems to have a different approach. I’m a fan of Therm-A-Rest’s solution – a stretchy elastic cord with a plastic toggle on either end. Therm-A-Rest calls it a SynergyLink Connector. The toggle slips through a small loop on the sides of the Vesper and then the cord feeds underneath your pad to slip through a corresponding loop on the opposite side of the quilt. The resulting tension is just enough to keep the Vesper from being drafty while still allowing for freedom of movement.
The system is simple, elegant, and versatile: there are two loops on either side of the Vesper, one high up on quilt and one about two-thirds of the way down. You can choose which loop you’d like to use based on your sleeping style.
Of course, you can also always just leave the strap at home (but why would you at 0.1 oz / 2.8 g). Therm-A-Rest seems to know that ultralighters love hacking away at extraneous bits of fabric: why else would they make it removable in the first place? This is, in fact, my only problem with the system. The SynergyLink connector is so small and so light and so easy to attach and remove that it is easily misplaced (if you leave it hooked into the Vesper it sometimes comes loose and falls to the ground when you pull the quilt out of the compression sack).
After nearly losing it several times I took to storing the SynergyLink Connector in other places: a sundries bag, inside a sleep sock, in a zippered compartment of my pack. Basically anywhere but inside the compression sack with the Vesper. In the future I might experiment with ways of permanently or semi-permanently affixing the connector to one of the loops. A small rubber band might do the trick.
Temperature Rating and Warmth
The Vesper 20F is comfort rated to 32 F (0 C) and limit rated to 20 F (-6 C). These numbers are worth digging in to, as they are one of the chief reasons to choose the Vesper over a competing quilt.
Much ink has been spilled over how temperature ratings in sleeping bags aren’t standardized in the same way that, for instance, R-Value in sleeping pads is. In fact, there is a standardized system, it’s just that not every gear manufacturer chooses to rate their bags according to it.
For instance, here’s a snapshot of the temperature specs for a competing quilt, taken from the product page of REI’s website.
Now here’s a snapshot of the temperature specs for the Vesper, also taken from the REI product page.
See the difference? Both products have a temperature rating, but only the Vesper has a tested lower limit and tested comfort temperature.
This is because Therm-A-Rest has on-site cold chambers and testing facilities that conform to the EN/ISO standards. Do other manufacturers have these facilities? Sometimes … but Therm-A-Rest seems to make it a point of pride to be accurate in their temperature numbers and they go out of their way to achieve EN/ISO certification on their quilts and bags.
Additionally, Therm-A-Rest has developed a handy visual graphic to help prospective buyers hone in temperature needs even more. Here’s the one for the Vesper.
Most companies are only going to give you one number, say, 20 F (-6 C). What does this number mean? Will you be comfortable at that temperature? Shivering? Bitterly cold but not dying? It’s different for every company, and they don’t always tell you which is the case.
This is why I so appreciate Therm-A-Rest’s attempts at transparency. I found their ranges to be right on: I was comfortable in a light beanie and base layer at 30 F (-1 C) and warmer. Any colder than that and I needed to start tossing on an extra layer or two (though not much). At 20 F (-6 C) I needed the Waterbear Hood and an insulating mid-layer like a fleece or long-sleeved shirt on top of my base layer. Temperatures in the teens required a down jacket or an additional quilt for maximum comfort.
Of course, this is all subjective. Experience and sleep temperatures vary wildly from person to person. But Therm-A-Rest is as precise and open about it as possible, and that is a great thing when making an expensive purchasing decision on a major piece of gear.
Cut, Design, and Special Features
Broadly speaking, you could divide quilt footbox styles into two categories: fixed and unfixed. The footboxes on the unfixed models, like the Nemo Equipment Banshee or the Jacks R Better Sierra Sniveler, cinch closed because the quilts themselves are designed to be opened all the way (blanket style) if desired. This “lay-flat” design is ideal for claustrophobic sleepers, drying out wet quilts, or (in the case of the Sniveler) wearing the quilt as a serape.
Therm-A-Rest goes with a weight saving, simpler approach: a fixed footbox. The result is a quilt that doesn’t open all the way like a blanket but also avoids the cold spots that are all but inevitable with a cinch-close footbox.
The Vesper’s footbox has an ergonomic structure designed to accommodate a back sleepers upward pointed toes without undue loft compression. Some quilt foot boxes are designed to accommodate sleeping pads in addition to hiker feet (see the Nemo Equipment Siren, read our review here) but the Vesper’s footbox is a “feet only” space.
The Vesper’s footbox is sewn with a “differential cut”, meaning the inner shell is cut in such a way as to allow the insulation to stay lofted even when pressure (from toes or ankles, for instance) is applied from inside the bag. A differential cut is valuable in preventing cold spots (particularly with horizontal baffles), and I’m happy that Therm-A-Rest chose to utilize one in the footbox of this product.
The Vesper’s draft collar is one of its best features. This narrow horizontal baffle runs along the top of the Vesper and closes from behind with a simple snap button. A bright green drawstring (with an extra large loop to accommodate gloved fingers) cinches the collar to the desired circumference. Far from being constricting, the collar is wide enough to be comfortable but lofty enough to be warm and cozy. I was shocked at how quickly I came to appreciate it.
Dimensions and Fit
I found the Vesper’s 75 x 58 in (191 x 147 cm) dimensions to be plenty large enough to accommodate my relentless nocturnal rotations. That being said, at 5’6, 165 lbs, I’m not the world’s broadest-shouldered backpacker. Hefty backpackers might want to go with a size long, which runs 79 x 61 in (201 x 155 cm) at the cost of an additional 2 oz (28 g). That size difference represents the limit of the customizations available for the Vesper I’m afraid. Customization is one of the benefits of the cottage industry quilt market, and if you like your sleep system precisely dialed in you might not want to go the Vesper route.
You’d be hard pressed to find a quilt of comparable warmth and weight that compresses down to a smaller size than the Vesper. In my opinion, this is one of the Vesper’s strongest selling points. When paired with an ultralight sleeping pad (like, say, the UberLite) you have a supremely warm and comfortable (for its weight) three-season sleep system that takes up a relatively small amount of space in a minimalist pack.
Personally, I’m not a fan of the four-point strap and lid style compression sack that comes with the Vesper. The sack itself is fine: perfectly sized for the quilt, well-constructed, and functional. I just find all those straps to be a little unwieldy and, well, un-elegant.
I prefer a roll-top style compression sack. But it’s very likely you couldn’t get the Vesper compressed down to such a diminutive size in a roll-top style sack, so I can live with the one that comes with the Vesper. (For what it’s worth, I haven’t tried seeing how the Vesper compresses in other styles of compression sacks … I’d love to hear what other users have accomplished).
Product Strengths and Limitations
- Excellent warmth-to-weight (and size) ratio
- Supreme packability
- Premium materials: soft DWR treated nylon & 900 fill RDS hydrophobic down
- Solid construction
- Differential cut footbox
- Design hits the sweet spot between useful features and minimalist aesthetic
- Collar is comfortable and nicely sized
- Sleeping pad connections system is elegant, functional, and weighs 0.1 oz (2.8 g)
- Some loose stitching after thirty nights of use (is likely a flaw in my sample product)
- Can’t be customized the way cottage brands can
- Sleeping pad connection system is easy to lose
- Can’t be opened like a blanket
For this comparison table, I chose quilts that weigh from 17.5 oz (496 g) to 20 oz (567 g).
|PRODUCT||WEIGHT||TEMP RATING||FILL POWER||BAFFLE ORIENTATION||HYDROPHOBIC TREATMENT||FOOTBOX DESCRIPTION||LINER AND SHELL FABRIC||PAD ATTACHMENT||SPECIAL FEATURES (draft tubes, poncho style, etc)|
|Therm-A-Rest Vesper||19 oz||20 F (-7 C)||900||horizontal, with small periminter side baffles||Nikwax||fixed||10D ripstop nylon||elastic pad cords||snap neck closure|
|REI Magma Trail Quilt||19 oz||30 F (-1 C)||850||hybrid vertical/horizontal||water-resistant||fixed, trapezoidal||15D ripstop nylon||cinching pad cords||adjustable insulated draft tube, button snap neck closure|
|Sea to Summit Ember||19 oz||25 F (-4 C)||750||hybrid vertical/horizontal||Ultradry||drawcord closure||15D nylon||four adjustable straps||can be opened like a blanket on warm nights|
|Katabatic Palisade||17.5 oz||30 F (-1 C)||900||horizontal||Hyperdry||fixed, trapezoidal||shell: Pertex Quantum ripstop .85 oz/yd2; liner: Pertex Quantum taffeta 1.0 oz/yd2||cord clip attachment system||down collar, cord clip system attaches to top of pad rather than underneath|
|Western Mountaineering AstraLite Baffled Top Quilt||17.5 oz||26 F (-3 C)||850||horizontal||none||fixed||shell: 7D nylon; liner: 10D nylon||two flat elastic loops||elastic-laced adjustable bottom closure|
|Enlightened Equipment Enigma||17.94 oz||30 F (-1 C)||850||U-shaped||Downtek||fixed, round||10D nylon||elastic straps and clip||snap and drawstring neck closure|
|Kammok Bobcat Trail Quilt||20 oz||45 F ( 7 C)||600||diamond shaped||Downtek||snaps and drawcord closure||Atmos 20D ripstop nylon||straps||underquilt conversion, can lay flat like a blanket|
|ZPacks Solo Quilt||19.5 oz||20 F (-7 C)||900||hybrid vertical/horizontal||none||fixed||7D Ventum ripstop nylon||flat clip and strap||30% overstuffed, flat clip and elastic cord neck closure|
|Nunatak Arc UL||19.4 oz||20 F (-7 C)||900||hybrid vertical/horizontal||Hyperdry optional||fixed||10D with customizable options||standard straps (running under pad) or shockcord (running under body) optional||optional edge tension control for high draft adjustability, drawcord neck closure standard|
I want to spend a few moments comparing the Vesper to another recent addition to the quilt market: The REI Magma Trail Quilt 30. This is a worthwhile comparison because both quilts are recent offerings from long-established gear manufacturers with track records for well-considered design and strong execution. Both quilts weigh 19 oz (538.6 g) and utilize some form of hydrophobic down. Both quilts have a fixed-footbox design, an adjustable collar with a button snap closure, and hybrid style baffles (the Vesper has horizontal baffles with perimeter side baffles, while the Magma has horizontal baffles across the torso and vertical baffles down the legs). Neither quilt can be customized beyond ordering different sizes (Regular and long for the Vesper, short, regular, and long for the Magma).
So, with similar features and similar weights, which bag is warmer? As we’ve examined, this question can be tricky. The Magma has a temperature rating of 30 F (-1 C). What does this mean, exactly? Hard to say. The best we can do is turn to REI customer support, which provides this feedback on a customer question.
So using this as a reference point, we can assume that both quilts will provide similar comfort at similar temperatures. But because the Magma isn’t ISO rated (as opposed to the Vesper, see the Temperature Rating and Warmth section of this review) we don’t know.
The Magma utilizes sewn-through baffles as opposed to the Vesper’s box-baffles, and I think that has to come into play warmth-wise in some way.
One thing that is measurable is this: the compressed size of both quilts relative to their width and length. The Magma packs down to 4.75 x 13 in (12 x 33 cm) while the Vesper compresses to 5.5 x 8 in (14 x 20 cm). That’s a significant difference inside a pack. Also, it’s quite an effort to get the Magma compressed down that small (this according to our forthcoming Magma review as well as anecdotal user comments on the REI website). On the other hand, it’s a cinch to get the Vesper into its sack and compressed.
The Vesper manages this win despite being two inches wider at the shoulders and having 1.5 oz (42.5 g) more fill weight than the Magma. Therm-A-Rest likely achieved this by using 10D fabric over the Magma’s 15D and 900 fill down over the Magma’s 850 fill.
These differences show up in the price tag, however. The Vesper retails for $379.95 while the Magma goes for $299.00. At those price points, you might just be getting more quilt for your buck with the Magma.
I was lucky to be able to test this quilt in such a variety of conditions and with so many different sleep system combinations. It performed well across the entire spectrum of my test: shaking off moisture and drafts, providing flexible temperature management, and keeping me warm at night while being virtually unnoticeable in my pack during the day.
This last point is the most salient to me, and the factor that places the Vesper on the “shelf of honor” in my gear closet. What is the ultralight ethos if not the utilization of well-designed gear that is as light as possible while still being extremely functional? That is the Vesper. It does its job with just enough frills (snap collar, pad connection system) to be effective but not enough to add unneeded ounces.
A focus on premium materials and intentional design choices means you end up with a quilt that provides ample coverage for all but the largest and most restless of sleepers. In addition, the Vesper compresses down to a size that is just a little ridiculous.
Review Rating: Highly Recommended
The Vesper 20F is a superior product: it excels in field performance, design, and material choice. Its warmth-to-weight and warmth-to-size ratio are top of class, and it handles inclement weather as well if not better than any other down quilt or bag I’ve come across. The design is precise and the manufacturing quality is as high as you would expect from Cascade Designs (which is to say, extremely high). The loose threads on my sample Vesper are not likely to be found on the consumer runs of the product.
My minor gripes like fabric color, stuff sack type, and an easily losable pad connector pale in comparison to the Vesper’s main strengths: just how warm of a quilt Therm-A-Rest manages to squeeze into such a small and light package. I consider the Vesper to be one of the top three quilts available at the moment, and as such I believe it deserves a Highly Recommended rating.
Where to Buy
- Buy the Therm-A-Rest Vesper 20F at REI.com.
- Need a quilt for warmer temps? Check out our review of Nemo Equipment’s Siren.
- How we acquired these products: Product(s) discussed in this review were either acquired by the author from a retailer or otherwise provided by the manufacturer at a discount/donation with no obligation to provide media coverage or a product review to the manufacturer(s).
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