Nathan VaporAir/VaporAiress 4.0 8L Hydration Vest Review
A comfort-driven hydration vest with easy-access pockets and plenty of storage for long trail runs
September 3rd, 2026
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Our verdict
The Nathan VaporAiress (women’s) and VaporAir (unisex/men’s) 4.0 hydration vest is designed for long-distance runners who want a vest that remains comfortable over long runs, has functional pockets that make it easy to access fuel and layers, and never feels cumbersome.
We tested the women’s Nathan VaporAiress 4.0 during winter, spring, and summer in Colorado, Arizona, and Utah. Runs ranged from short, easy trail runs to a marathon-length stretch of the Cocodona 250 race in Arizona while pacing. We mostly wore it in clear conditions, but running on really hot summer days allowed us to test its moisture-wicking abilities.
The greatest strength of this hydration vest is its comfort—not only does it fit well and adjust easily, but it also doesn’t bounce too much, and it hardly feels noticeable over long runs (as much as a hydration vest can feel unnoticeable). The mesh back panel aids in breathability and is quick-drying. The front pockets make accessing fuel, your phone, sunglasses, or SPF lip balm easy while moving, and there’s enough capacity in the back for extra layers. It comes with a 2L hydration bladder, and the front pockets are compatible with 20-oz flasks.
Nathan VaporAir/VaporAiress 4.0
Men's / Unisex
Women's
One of our biggest gripes with the vest is that the hydration straw (or hose) doesn’t stay put in the sternum clip and slides down, which means the hose can flop around more. We had to tuck the straw under a front strap to keep it from bouncing around annoyingly. We also wish the vest came in larger sizes for plus-size runners. The version we tested fit us well, but the women’s vest only goes up to size XL and the unisex/men’s to XXL, which excludes people with bigger bodies who want a comfortable hydration vest to support their training.
This vest comes in three women’s sizes (XXS-XS, S-M, and L-XL) and three unisex sizes (S-M, L-XL, and XXL), so if you fall within those size ranges, this pack will likely fit you comfortably. With minimal bounce and thoughtful pocket placement, this is a trusty hydration vest that will keep you prepared and hydrated over long runs.
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Nathan VaporAir/VaporAiress 4.0 hydration vest specifications
Price: $160
Men’s (unisex) weight: 7.7 oz (without bladder), 10.7 (with bladder)
Women’s weight: 7.7 oz (without bladder), 10.7 (with bladder)
Capacity: 8L
Hydration included: 2L bladder
Bottle compatibility: Yes
Number of pockets: 7, and a main compartment
Fit system: Quick-Fit adjustment system (wrap-around panels, bungee cords, adjustable front clips)
Material: 42% polyester/32% nylon/14% spandex/8% polyoxymethylene (POM)/3% rubber
Men’s sizes available: S-XL
Women’s sizes available: XXS-XL
Best use: Trail running, long runs, day hikes, and peak bagging
Comparison table
| Running Vest | MSRP | Men's Weight | Women's Weight | Gear Capacity | Hydration Included | Exterior Pockets |
|---|---|---|---|---|---|---|
| Nathan VaporAir/VaporAiress 4.0 Men's Women's |
$160 | 7.7 oz | 7.7 oz | 8 L | 2 L bladder | 5 |
| REI Co-op Swiftland 5 Men's Women's |
$110 | 9.0-10.0 oz | 8.5-10.5 oz | 5 L | 1.5 L bladder | 5 |
| Salomon Adv Skin 12 Men's Women's |
$165 | 8.7 oz | 8.7 oz | 12 L | 2 flasks | 9 |
| Kiprun Women's 8L Women's |
$119 | N/A | 8.5 oz | 8 L | 2 flasks | 11 |
| Kiprun Men's 10L Men's |
$145 | 8.5 oz | N/A | 10 L | 1.0 L bladder | 11 |
Best for
Trail runners who want a hydration vest that fits comfortably with a soft, breathable material, has a little stretch to move with you, and is easy to adjust
Long runs where you’ll need to carry lots of water, fuel, layers, etc.
Day hikers and peakbaggers who want a smaller pack for speedier, more agile movement
What we liked
Wrap-around panel adjustability is soft, a little stretching, and generally comfortable while limiting bounce
Back mesh panel is quick drying, breathable, and reduces sweat build-up
Pockets are functional and easy to access, and back storage is plenty spacious for layers
What could be better
Hydration straw doesn’t stay put in clip and can slip down while running, causing the hose to flop around more
No plus-size options
Our men’s tester didn’t like the wrap-around fit as much as other vests
How we tested the Nathan VaporAir/VaporAiress 4.0 hydration vest
We tested the women’s Nathan VaporAiress 4.0 and men’s VaporAir 4.0 hydration vests on runs and hikes in the winter, spring, and summer in Colorado, Arizona, and Utah. Most runs and hikes ranged from 3-10 miles in the Colorado Front Range on dirt and rocky trails. Our women’s tester also wore the Nathan VaporAiress while pacing 10-mile and 26-mile sections of the Cocodona 250 race. Both of those sections were done at night and required carrying a lengthy list of supplies (lots of layers, poles, fuel, water, first aid, etc.). We also tested these hydration vests on hikes and scrambles in Colorado and Arizona.
While best for long trail runs, we also found the Nathan VaporAiress to work well for carrying water, a jacket, snacks, and other small items on a day hike.
Most testing was done in clear, dry weather across three seasons. Running in the heat of the summer allowed us to test how the pack handled sweat. During runs in the winter, we were able to test how well the straw withstood freezing temperatures.
We also tested this hydration vest alongside other hydration vests featured in our Best Running Hydration Vests guide and our upcoming Best Running Hydration Vests for Women guides.
Performance in the field
Fit and stability
The Nathan VaporAir/VaporAiress 4.0 uses a Quick-Fit adjustment system, which is basically an interior panel that wraps around the torso and has exposed front toggles for adjusting, even while running. If you fall in the women’s XS-XL or unisex/men’s S-XXL size range, you’ll find this hydration vest fits snugly without feeling too snug—i.e., it won’t bounce around, and it’s hardly noticeable, which is just what you want from a hydration vest.
The front sternum straps can be adjusted laterally, and the buckle adjustments are easy to adjust while running.
The side toggles and front clips make adjustments simple, and the wrap-around panels are soft, with a breathable mesh, so the vest stays comfortable over long runs. Here are the measurements at the chest for each size:
Women’s:
XXS/XS: At sternum: 28-32.5 inches; bust: 32-34 inches
S/M: At sternum: 33-36.5 inches; bust: 36-38 inches
L/XL: At sternum: 37-40.5 inches; bust: 40-42 inches
Unisex/Men’s:
S/M: 35-40 inches
L/XL: 41-46 inches
XL: 47-51 inches
Hydration access
The hose has a tendency to slip down in the clip, causing the hose to flop around more while running. We got around this by tucking the hose under the bottom sternum strap.
This vest comes with a 2L bladder with a quick-release hose that has a bite-valve and shutoff switch. This is enough water for most runners to last about 2-3 hours. You can also fit two 20-oz flasks in the front pockets, which could extend your carry another hour or two.
The hose makes hydrating on the go easy. However, we found the straw a little annoying because the clip wasn’t tight enough to keep the hose from slipping down and flopping around. We got around this by tucking the straw under the front sternum straps to keep it in place.
Storage and organization
The interior of the Nathan VaporAir’s 8L main compartment.
The vest has an 8L capacity and was just enough for a 26-mile nighttime stretch of technical trail running. You can fit a surprising amount of gear/layers in the main compartment, even with a full bladder. The five front pockets and two side pockets have a little stretch to them, so you can stuff them pretty full with gels, snacks, keys, SPF lip balm, your phone, your sunglasses, or any other small items you want easy access to.
The longer our women’s tester tested this vest, the more she got into a rhythm with what she liked stored where. For example, the zippered pocket holds her keys and lip balm, the right stretch pockets store her phone and fuel, and the left stretch pockets store her sunglasses and more fuel. If her run was really long, she’d use the side stretch pockets for more fuel storage. Over long runs, this vest starts to feel like home.
Comfort
According to our women’s tester, the overall comfort of this hydration vest is one of its greatest strengths. However, our men’s tester found the wrap-around fit less comfortable than the Salomon ADV Skin 12 vest (which our women’s tester hasn’t yet tested).
The 3D mesh interior is soft and breathable, the side toggles and front sternum straps allow for a more personalized fit (that you can easily adjust while on the move), and even when stuffed full, the pack doesn’t bounce much. This has become our women’s tester’s go-to hydration pack, especially for long trail runs and day hikes.
Durability
We have been wearing this hydration vest over hundreds of miles since February 2026 and have experienced no durability issues. The construction has held up, no parts have broken, and it’s still in great shape.
Features
The zippered key pocket has a small carabiner and whistle.
8-liter storage capacity
The Nathan VaporAir/VaporAiress 4.0 hydration vest comes with a 2L hydration bladder and a total of eight liters of storage space. In practice, this lasted us up to a 26-mile stretch of the Cocodona 250 course while pacing a friend (though if we were racing, we might have wanted a little more capacity).
The Nathan VaporAir and VaporAiress have 8L of capacity, which is plenty for the 2L hydration bladder, layers, snacks, and whatever else you may want to carry on a trail run.
Adjustable sternum straps
There are two adjustable sternum straps that clip in the front and are easy to use and adjust.
Side adjustment toggles
The side adjustment toggles are located on the front of the vest so you can easily reach down and adjust them as needed while you’re running.
Multiple stretch storage pockets
The front pockets can fit two 20-ounce flasks, fuel, and other small items.
The two side stretch pockets, four front stretch pockets, and one zippered pocket all open on top and are easy to access, even on the go. The stretch means you can stuff them pretty full with plenty of fuel for long runs. The zippered pocket also has a small whistle attachment and a small carabiner for keys.
Rear storage compartment
The main storage compartment holds the 2L hydration bladder and still has plenty of room for whatever gear you’ll need while running. We often stored a running jacket, a Buff, hat, gloves, and other layers in the compartment, and still never experienced much bounce.
3D mesh shoulders and back
The 3D mesh construction on the interior of the vest (the parts that touch your body) allows for increased airflow. This helps to increase breathability, limit sweat build-up, and lower (but not eliminate) the likelihood of your gear in the main compartment getting wet from your sweat.
Bite-valve with shutoff switch
You can twist the mouth of the hose shut to prevent water leakage. This is really easy to twist while running.
Trekking pole attachment loops
This vest has pole keepers on the lower back with bungee adjustments so you can access your poles without removing the vest. We were able to use this without taking off the pack, but not seamlessly while running, as the poles get caught on the bungee cords easily. This could improve with more practice, though.
Bungee back for external storage
Bungee cords on the back allow you to externally stow layers. Our main tester also used this cord to clip a Kula cloth on long runs.
Reflective elements
This hydration vest is not reflective. The Nathan HyperNight QuickStart 3.0 4L hydration pack, however, is fully reflective if you’ll be running in the dark. You can also check out our Best Reflective Gear for Running in the Dark guide to learn more about staying seen and safe while running in the dark.
Sustainability/ethics
Nathan does not share any specific sustainability or social responsibility efforts on their website. They simply state they “seek to embed corporate responsibility into the stewardship of our core business activities. We incorporate social and environmental thinking in our planning, supply chain and business operations. We encourage employees to volunteer with community partners and we seek to combine our expertise and competencies with those charity and community groups so we can bring extra benefit to the communities in which we operate.”
This is pretty vague, and we would like to see more concrete sustainability and workplace efforts from the brand.
Men’s/unisex vs. women’s Nathan VaporAir/VaporAiress hydration vest differences
The difference between the Nathan VaporAir (men’s/unisex) and VaporAiress (women’s) vest is in the fit. The women’s-specific design has a more contoured fit around the wrap panel, shorter shoulder straps, and a shorter torso. The features, material, and capacity are otherwise the same.
Should you buy the Nathan VaporAir/VaporAiress 4.0 hydration vest?
Buy if you want a comfortable, easy-to-adjust hydration vest that can carry enough gear and water for most runners to last up to roughly six hours and doesn’t bounce much.
Skip if all your runs are under an hour and you don’t need to carry much, or if you need a size above XL (women’s) or XXL (men’s). You can also skip if you want to spend under $160, as there are options available at a lower cost.
Where to buy the Nathan VaporAir/VaporAiress 4.0 hydration vest
The Nathan VaporAir and VaporAiress 4.0 8L hydration vests are popular, so you have options when it comes to retailers. Here are some of the pros of the retailers.
REI
Pros: 100% satisfaction policy for 1 year; 10% dividend for members.
Amazon
Pros: Free 2-day shipping with Amazon Prime membership (can be same-day delivery in major metropolitan cities)
Nathan Sports
You can sometimes find more options when purchasing directly from the manufacturer. Sometimes, purchasing directly from the retailer can make it easier if you need to make a warranty return due to a defect.
Advice on where to buy
In general for gear, we recommend purchasing from a place with easy or free returns, like REI.
Similar hydration vests
REI Co-op Swiftland 5
MSRP: $110
Capacity: 5 L
Included hydration: 1.5 L bladder
Women's-specific fit available: Yes
Weight: 9.0-10.0 oz (men’s), 8.5-10.5 oz (women’s)
We tested the men’s/unisex and women’s REI Co-op Swiftland 5 hydration vest. We appreciated the extended size ranges compared to most hydration vest options, the range of adjustability to fit, the general comfort and stability over long runs, and the plentiful pockets.
While we found the Nathan VaporAiress to be more comfortable and have easier-to-use clasps, the Swiftland 5 is a worthy budget option if you want to save $50. In fact, we named it our best affordable pick in our Best Running Hydration Vests guide. Learn more in our in-depth review of the REI Co-op Swiftland 5 hydration vest.
REI Co-op Swiftland 5
Men's
Women's
Salomon Adv Skin 12
MSRP: $165
Capacity: 12 L
Other capacities available: 5 L
Included hydration: Flasks
Women's-specific fit available: Yes
Weight: 8.7 oz
The Salomon Adv Skin 12 is a popular running vest, and the overall winner in our Best Running Hydration Vests guide. This vest has even more accessible pockets than the Nathan VaporAir/VaporAiress 4.0. It has three pockets on each shoulder strap, another in the stretch mesh that connects the front straps to the back of the pack under your arms, and one more pocket on the back of the pack, with side access on either end. Our men’s tester also prefers the overall fit, material comfort, and adjustability of this vest to the Nathan VaporAir. Learn more in our in-depth review of the Salomon Adv Skin 12 hydration vest.
Salomon Adv Skin 12
Men's
Women's
Kiprun Women’s 8L Hydration Vest/Men’s 10L Hydration Vest
MSRP: $119 (women’s), $145 (men’s)
Capacity: 8L (women’s), 10L (men’s)
Other capacities available:
Included hydration: Two 500mL flasks (women’s), 1L bladder (men’s)
Women's-specific fit available: Yes
Weight:
The Kiprun hydration vests are excellent budget options, as they cost less than most other vests without sacrificing features and a comfortable, adjustable fit. Both the women’s 8L vest and men’s 10L vest have a whopping 11 pockets (our women’s tester actually briefly lost her travel-size SPF stick and lip balm because they were in pockets she had forgotten about).
The women’s-specific fit has a patented lateral tightening system to adapt to the wearer’s curves, and two height-adjustable front straps. The shape of the 500ml flasks was revised to free up the chest, but during testing our women’s tester found them to be kind of in the way of her arm swing.
While I appreciate the women’s vest seems to follow an intentional design plan rather than the “shrink it and pink it” we often see with women’s-specific gear and apparel, I was disappointed that the men get a 1L hydration bladder and the women don’t have that option. But if you don’t mind not having a bladder, this vest is comfortable, highly adjustable, and has plentiful pockets for long runs.
Kiprun Women’s 8L Hydration Vest/Men’s 10L Hydration Vest
Women's 8L
Men's 10L
Why you should trust us / About the author
Becca Downs ran D1 cross country and track for Indiana University—Purdue University of Indianapolis (IUPUI) and continued racing everything from elite miles to an ultramarathon in her post-collegiate years. She earned a USATF Level 1 certification and coached boys and girls high school cross country and track in Indianapolis for four years. Becca then joined the IUPUI women’s distance coaching staff as a volunteer assistant coach in 2020-2021.
She geeks out on trail running, track and field, and cries every time she watches a marathon (they’re just so beautiful!).
After notching a few small FKTs under her belt, she was diagnosed with hip arthritis and now channels her passion for running into coaching, crewing, writing, creating training plans for her friends, hiking, snowshoeing, and running as much as her hip allows. She earned her MFA in Creative Writing from the Mile-High MFA Program at Regis University. Becca is based in Denver, Colorado.
Find more of Becca’s reviews on her Treeline Review author page.
