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Arc'teryx Phase SL Brief Review

The Phase SL Brief is a quick-drying baselayer that falls flat on comfort
arc'teryx phase sl brief travel underwear women review
Arc'teryx Phase SL Brief
Credit: Arc'teryx
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Price:  $39 List
Pros:  Quick-drying, lightweight
Cons:  Uncomfortable, too tight
Manufacturer:   Arc'teryx
By Lauren DeLaunay ⋅ Senior Review Editor  ⋅  Apr 26, 2018
Our Editors independently research, test, and rate the best products. We only make money if you purchase a product through our links, and we never accept free products from manufacturers. Learn more
  • Comfort - 30% 4.0
  • Fit - 30% 4.0
  • Drying Time - 30% 9.0
  • Packability - 10% 8.0

Our Verdict

Arc'teryx discontinued the Phase SL Brief.

Arc'teryx has long been equated with greatness in the outdoor clothing industry, so we had to see what they were pumping out in the underwear department. The Phase SL Brief shocked us with a $39 price tag, but we were eager to see how it stacked up against the competitors. Unfortunately, we found uncomfortable materials and a tight, awkward design that left us hanging up our briefs and looking for more. While fast to dry and impressively light, we were hoping for a bit more stretch and softness.

Our Analysis and Test Results

The Phase SL Brief from Arc'teryx is an impressively light, quick-drying pair of undies. Unfortunately, it falls flat on comfort. Its tight, awkward design was our least favorite in this test, and at a steep $39 price tag, we're not likely to recommend it.

Performance Comparison

arc'teryx phase sl brief travel underwear women review - the phase sl undies seem to prioritize drying time over comfort.
The Phase SL undies seem to prioritize drying time over comfort.
Credit: Lauren DeLaunay


As much as we here at OutdoorGearLab strive to be clean, unbiased slates, we have to admit we were a bit excited to see what Arc'teryx, maker of some of our favorite outer layers, had come up with for our under layers. Unfortunately, we were confused the moment we pulled the Phase SL Brief out of its packaging. We were quickly unimpressed by both the material and seams.

arc'teryx phase sl brief travel underwear women review - the bulk material of the phase sl is soft enough, but the waistband...
The bulk material of the Phase SL is soft enough, but the waistband lags behind.
Credit: Lauren DeLaunay

The bulk material is a decently soft polyester, though nothing to write home about, while the seams and waistbands are made of an itchier fabric. We prefer either a seamless design or a pair with a thick, supportive waistband.

The one saving grace of the Phase SL Brief is the breathability. Airflow is undeniably vital to overall comfort, especially while traveling or exercising. This is the one thing the Phase SL does well, though there were other pairs, like the Patagonia Barely Hipster that were just as breathable without compromising comfort.


Once again, we're a little bit stumped on the design decisions behind the Phase SL Brief. With a stiff, slightly itchy material and an awkwardly narrow crotch, we were less than impressed. The first thing we noticed was the tight fit, though this may be resolved by sizing up from your normal underwear size.

We were also confused by the high leg openings, and that lend themselves to wedgies and found the waist to be of a higher-rise than we usually like. The crotch is very narrow and does not provide enough coverage.

arc'teryx phase sl brief travel underwear women review - the phase sl brief features an awkwardly narrow crotch and too-tight...
The Phase SL Brief features an awkwardly narrow crotch and too-tight leg openings.
Credit: Lauren DeLaunay

The waistband appears to be stretchy, but our testers quickly found that the overall elasticity of the Phase SL is limited by the bulk material. One of the least stretchy models we reviewed, the leg openings are stiff and have much less give than we would like to see, especially on underwear designed for active use. Lastly, the Phase SL comes with a large tag on the inside and a small, hard label on the back of the waistband. While the hefty tag can be cut off, we prefer products with a more seamless design.

Drying Time

The major saving grace of the Phase SL is drying time. This product was fully dried in 40 minutes, the fastest of any we tested. As soon as we wrung these undies out by hand, we knew that they would be a top contender in this metric. They felt nearly dry after towel-drying, after 20 minutes they were nearly completely dry, the only exception being the crotch, which is reinforced and therefore twice as thick as the rest of the material.

arc'teryx phase sl brief travel underwear women review - the phase sl dries in an incredibly fast forty minutes!
The Phase SL dries in an incredibly fast forty minutes!
Credit: Lauren DeLaunay

Drying time is essential to travel for many reasons. The quick-drying material makes for more comfort while wet and sweaty. It also makes it easier to hand-wash and air-dry while on the go, and essential function if space is limited in your pack or suitcase. The Phase SL no doubt excelled in this category.


Packability is an important metric when scoring travel underwear, but since all of the products in our test were so light, it was a little difficult to distinguish. The Phase SL was noticeably lighter and smaller than some of its competitors, however. At just .8 oz (22 g), this was one of the lightest models we tried. In our folding test, the Phase was significantly thinner than some of the other undies, and we found its thin material easy to stuff into gaps in our packs and carry-ons.

arc'teryx phase sl brief travel underwear women review - the phase sl brief is teeny tiny and so easy to pack on any adventure!
The Phase SL Brief is teeny tiny and so easy to pack on any adventure!
Credit: Lauren DeLaunay

Best Applications

As a synthetic model, the Phase SL is best suited for environments where quick drying is essential. Whether participating in water sports or getting drenched in sweat is your thing, or if you're looking for a pair you can wash and wear in a matter of minutes, the Phase SL Brief would be right at home. That being said, there are many models on the market that achieve these ends with more comfort, making it difficult to find the perfect application for this product.


At a whopping $39, the Phase SL Brief is tied for the most expensive pair of underwear tested in this review. And to be honest, we're not sure why. While wool is generally accepted to be more expensive than synthetics, we're baffled by the price tag on this polyester product. Due to its poor comfort and fit scores, we fail to see the value in this expensive pair of briefs.


Our testers were sad to report that the Arc'teryx Phase SL Brief was the only pair of undies they tested that they didn't want to wear. We found it to be too tight and constricting, which ultimately could not beat out its great performance in packability and drying time. Yes it's breathable and yes it's quick-drying, but unless seconds are of the essence, we'd be happier to recommend other more comfort models.

arc'teryx phase sl brief travel underwear women review - sitting, waiting, wishing, for the phase sl to be a little more...
Sitting, waiting, wishing, for the Phase SL to be a little more comfortable!
Credit: Lauren DeLaunay

Lauren DeLaunay
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