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Arc'teryx Rho LT Zip - Women's Review

Long Underwear for Women

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Editors' Choice Award
Price:   Varies from $87 - $125 online  —  Compare at 5 sellers
Pros:  Cozy fabric, warm, versatile, stylish
Cons:  Expensive, less breathable
Editors' Rating:     
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Manufacturer:   Arc'teryx


When you put on the Arc'teryx Rho LT Zip -Women's, it is pie in the sky, love at first wear - or so say our many testers. This base layer, which won our 2015 Editors' Choice Award, is an ultra-versatile, warm, and cozy long underwear top that will serve you well on all missions. Be it your first date with that dreamy guy from across the climbing gym or putting up your first intrepid ascent of the season. The fleece interior provides a nice fuzzy layer that sits close to your skin. If you anticipate it being warm outside, go ahead and put a tank top underneath - it will layer just right. If it's cold, don't worry about static cling getting all up in your business - there was none seen here. Our ladies truly loved its handy stash pocket on the shoulder and the zip collar, but were left wishing for thumb loops to make it extra versatile.

With the good there is a tiny bit of bad that comes in the form of breathability. Even though Arc'teryx calls this a lightweight piece, we found it to be rather warm and not the most optimal for more aerobic sports like running or backcountry skiing when it was above 50 degrees F and you're working hard. In fact, we would go as far to say that it fits into a midweight category more appropriately than lightweight. We found that it did not release heat as effectively as other garments like the Smartwool NTS 250 Crew - Women's. All that said, the Rho LT still took away the prize this year because of its great construction, durability, stretchy and flattering fit, and its overall versatility. Our Editors' Choice Winner is an ideal all-around base layer for multi-day hikes, climbing trips, biking, or whatever your heart desires. Just leave it at home for warm spring days or highly aerobic activities.

RELATED: Our complete review of long underwear - women's

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Analysis and Hands-on Test Findings

Review by:
Amber King
Senior Review Editor

Last Updated:
May 10, 2015
The Arc'teryx Rho LT Zip is a warm and versatile midweight layer that won our love and our Editors' Choice Award for 2015. This cozy layer features a zip collar with a convenient stash pocket and great temperature regulating technology that was above and beyond our expectations.

Performance Comparison

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Alison Lay lays it all out! A great fit, versatile features, and good temperature regulation makes this our 2015 Editors' Choice Award Winner.


This layer is so roasty, toasty warm! In fact, we found that it was warmer than most of the long underwear tested. As a result, we believe it fits more correctly into a midweight category. The 84% polyester and 16% elastane construction provides ample warmth on cool days as a stand-alone piece, and performs even better when paired up with an insulative layer. We found that it effectively wicks away moisture during our running and aerobic tests on cooler days, but we had to take it off on days where the mercury was above 50 degrees F.

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Warm and toasty! We were able to skin and ski in this layer without layering up. The fleecy fabric on the interior of the shirt makes it feel nice and cozy. Even though breathability is relatively limited, it's still a really high performing piece that we loved!

Not only that, but the face fabric is able to actually cut the wind to a certain degree, making it a perfect stand-alone piece when you need something that will 1) regulate your body temperature while moving; and 2) keep you warm when at a stand still. When climbing in Red Rocks Nevada on a windy day, two testers wore two different base layers - the REI Space Dye Zip-T and the Arc'teryx Rho LT Zip. The tester wearing the REI Space Dye was incessantly cold every time a wind came through and was forced to put on a jacket, where the Rho kept the other tester warm. What more can we say than that? A great layer that regulates temperature while on the move, and keeps you warm while you're standing (or hanging) still.

If you're looking for a merino wool long underwear top that is actually warmer than our Editors' Choice winner, but lacks the windproof barrier, check out the Smartwool NTS 250.


Breathability and warmth do go hand in hand; however, we found that when comparing other long underwear shirts to the Arc'teryx, the others were a little more breathable. Even though the Rho LT has a zip-up collar that allows you to release heat when it gets too warm, some of our testers found that the release wasn't enough. The fleece on the inside of the shirt retained heat really well and air flow seemed to be obstructed by the tightly woven fabric. As a result, it scored low points for breathability. That said though, it still did regulate heat well enough still be incredibly functional, but not as well as some other pieces. This is a trade-off for integrating a tight knit face fabric. If you're looking for a base layer that is incredibly breathable (but much less warm), check out the Under Armour Base 2.0 Crew - Women's.

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When the weather showed signs of rain, we chose to wear this without a tank (it was supposed to be super cold!). Though when the temperatures cranked up half way through this 10 mile run the author was forced to do some running in her bra. Due to a lack of breathability, this layer is not recommended for running on warm days.

Layering Ability

Putting things under or over this shirt is no problem. Like the REI Space Dye Zip, we loved the layering. The Rho LT's face fabric is nice and slinky smooth; even better, it doesn't generate static cling like the Smartwool NTS Mid 250 Crew. What's more is that unlike the Under Armour Base, the Rho is so thin that it doesn't add extra bulk to your layering set-up. Wear this as a standalone top or as a part of a functional layering system.

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The Arc'teryx doesn't cling or get all twisted. The tight, stretchy fabric hugs the body to make layering over and under easy as pie!

Comfort & Fit

Do you love the soft, luxurious feeling of micro fleece against your skin? Some women do, and some women don't. The majority of our testers agreed: wearing the Arc'teryx Rho feels like you're being wrapped in a cozy blanket all day long - and they loved it! Its slim, athletic fit is quite flattering and hugs your body in all the right places. Some of our testers mentioned that it fit tight across the shoulders, so if you do have wide shoulders, be sure to try this on first or size up.

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Snug like a glove! This polyester blend long underwear feels good and has the right lengths wherever you need it. We especially loved its zip collar that lended additional versatility.

We really loved this base layer's luxuriously long torso, which is cut similar to the REI Space Dye. It's long enough to sit between your bum and hips and has nice long arms. We also loved the versatility and comfort of the zip neck, but wished for a set of thumb loops. Finally, it has a special stash pocket for anything that you might need on the go…be it cash, a key, or a little something else for your mission. If you're more interested in a relaxed fit with a merino wool fiber instead of a synthetic, check out our Top Pick for Comfort, the Smartwool NTS Mid 250.

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Stash pockets are sweet! The Arc'teryx Rho was the only top that had an extra stash pocket. Super handy for keys, cash, or whatever little extras you might need on the trail.

Drying Speed

Planning on heading out on the river where you might get a little wet? Have no fear, the Arc'teryx Rho LT layer is here! Although it didn't dry as quickly as the Under Armour 2.0, this layer was the second fastest to dry out in our tests. Like the other synthetics we tested, including our Best Buy Award Winner, the Patagonia Capilene 3 - Women's and the Hot Chillys Micro-Elite Crew - Women's, the Rho dried out quickly, a quality that is especially valuable if you plan to spend several days in the backcountry.


This was that only shirt we tested that didn't show ANY wear and tear after 3 months of intensive use except for the name "Arc'teryx" rubbing out on the collar. Even after rubbing it on cliffs, stuffing arms into cracks, and letting it sit next to our dirty skin for days on end, we didn't notice any pilling or stitching fly aways. The odor blocker built into the fabric seemed to work well without any noted odors either. Like the Micro-Elite Hot Chillys, this is a highly durable piece that you can expect to use for many years.

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After pawing through this top for any sign of wear and tear, we came up short. The tightly knit face fabric and seams had no pilling while everything else remained in tact. No shrinkage, just consistency through the months. Way to go Arc'teryx!

Best Applications

This is a great all- around piece that you can take hiking, climbing, or out on the town. Don't be afraid to layer over or under and enjoy it as a base layer or to wear alone. Like most of the shirts tested, we wouldn't recommend this for highly aerobic sports like running unless the temperatures are chilly because of its inability to release heat quickly enough. But we WOULD recommend it for everything else! Enjoy!

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Alison Lay sure was a bit ballsy on this route. Fifty feet of hard and committing climbing will build up a sweat! After finishing her climb, she sat on a windy perch for 20 minutes longer. When asking her how she was doing temperature wise, she replied "Just fine!" Since this top demonstrated a great ability to wick moisture and retain heat, we thought multi-pitch rock climbing, among many other outdoor pursuits, was a perfect purpose for this piece.


The price tag of $125 is a little steep in our opinion and was a deal breaker for most of our testers. If you have a few extra bucks, don't be afraid to throw it at this high quality and versatile shirt. But if you're looking for a more affordable piece with similar features, check out the REI Space Dye or the Hot Chillys Micro-crew Elite, both of which performed well across the board.


A great all-around piece that has earned its place as our 2015 Editors' Choice Award Winner. From the moment you put it on, layer it up, and take it off, you will love it. Take it hiking, biking, or climbing and enjoy!

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Heading back to the car after a day of skiing with the dogs and Sophia. One of the many places the Arc'teryx Rho LT can go.

Other Versions

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Rho AR Zip Neck
⁃ Weight - expedition (thicker than the Rho LT)
⁃ Material - Polartec
⁃ Insulated
⁃ AR stands for "All Around"

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Phase SL Zip Neck
⁃ Weight - silkweight (lighter than the Rho LT)
⁃ Material - Polyester and polypropylene
⁃ Best used for aerobic interval activities
⁃ SL stands for "Super Light"

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Phase AR Zip Neck
⁃ Weight - mid-weight (thicker than the Rho LT)
⁃ Material - Polyester and polypropylene
⁃ Best used for aerobic interval activities
⁃ AR stands for "All Around"

If you are looking for a great pair of long underwear bottoms to go with the Rho Lt, check out the Rho AR bottoms.
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Rho AR Bottoms
⁃ Weight - mid-weight
⁃ Material- polartec
⁃ Thigh pocket
⁃ AR stands for "All Around"

For the guys, check out the Arc'teryx Rho LT Zip Neck - Men.
Amber King

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Most recent review: May 10, 2015
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