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Optimize your performance with our collection of running base layer tops, designed for ultimate comfort and support. Crafted from moisture-wicking materials, these tops keep you dry and comfortable during your runs, while lightweight fabrics ensure breathability. With a snug fit that moves with you, our base layers provide essential warmth without bulk, making them perfect for layering in any weather. Explore a variety of styles and colors to find the ideal base layer top that enhances your running experience and helps you achieve your fitness goals.
$55.97
WAS: $100.00*
What seems like another fleece, after my 7 miles sweaty run, the shirt is not soaked through in sweat and I still look good wearing it. ... Warm and comfortable layer, washes well with no shrinkage or
5
Mom2025
Got this for my daughter, she is a teacher. Her room is cold and then she has bus duty periodically. So the 4. 0 is perfect for being somewhat sedentary. Surprisingly, actually keeps her warm! She is a chilly person normally, so cold temps are miserable for her. We 've tried many products. The Under Armour is work the investment!
5
KarenK11
I am always cold. This is the solution! Love it!
5
East Coaster
These are the best long underwear going. I mind the cold but not when wearing these.
5
Jea970
The fit is loose but not so lose that I would exchange for a smaller size. The shirt is warm but not too warm when inside. Outside it keeps me toasty at 30 degrees and I ’ m always complaining of being cold. All in all, I ’ m very happy with this purchase.
5
I recently purchased the Under Armour Base 4. 0 Crew, and it's exceeded expectations. This top delivers comfort, warmth, and performance.
$30.97
WAS: $70.00*
I love it because I don ’ t get too hot while running, but stay warm enough when it ’s cold outside. ... This product is my go- to for cold weather runs ... It ’s perfect and is now my preferred 1st layer of up to 4
5
NonaElk
As expected wonderful. It ’s my third one
5
Rtin93
Great material fits really well Definitely going to be useful when worn during colder weather and feel like going for a run at the time
5
BiaE
Really warm underlayer. Used to ski on freezing temp and this plus good ski jacket was enough… even when it was snowing… The only thing is that it feels way different then the 2. 0 shirt. I also have one of that and the 3. 0 is more stiff and feels smaller. Specially in the neck and chest.
5
mrsguzzie
I purchased this Base Layer 3 shirt when I visited our local outlet store to place an order for another Under Armour shirt I liked. This shirt is thicker than a normal under layer shirt but is still comfortable if you wanted to wear additional layers. The cut of the shirt is super nice you might not want to hide it, though! It has thumb hole openings which are nice. I wore it alone several times since I bought it and was pleased at how well it kept me warm. I liked it so much I went to get a second one. They had sold out of the 3s but I snagged a 2 at least! My only negative comment would be it looks wrinkled when you remove it from the dryer. I only air dried it so maybe some heat might have gotten the wrinkles out. It's black so not that noticeable. Great shirt. I tried to get a 2nd one so obviously am happy with my purchase!
5
Stacy321
My husband has a few base layers and he loves them. I love the women's cut/size. It fits well and is super warm
$75.97-$145.00
WAS: $120.00-$145.00*
as one of our heaviest base layer tops and best base layers for cold weather, this garment uses 100% responsibly sourced merino wool, shoulder panels, and a flatlock seam construction to help minimize chafing as well as help keep you comfortable and temperature- regulated as you enjoy high-...
$90.00
It did a great job keeping me warm in those temps even with wind. ... The sleeves are long which I love. ... This sweater is comfortable, soft and a great layering piece for the
5
T Oot
Just came back from Banff Canada and wore this base layer everyday. I was warm and dry in sero degree weather!
5
Terri350
They fit great, feel great, and are really warm. I will buy them again!! Not sure what else to say but they require a longer review. I really, really, really, really like these base layer tops!!
5
Mkt5308
[ I 'm tall with long arms and sometimes merino is too short in the sleeves, not this time, fit is great medium is medium. Pistachio color is bright and fun
5
Dsrote
[ I purchased a smart wool base and fell in love. it ’s easy to clean and amazingly warm for its light weight! i would buy other colors if available.
5
Silvercurls
[ Bought my Smartwool Women's Classic All- Season Merino LS Base Layer Tops just in time for the cold weather in the “ D ”. Best referral from a friend ever! Not only do I look good because they fit beautifully but are lightweight; so I ’ m not bulky 😊 whether worn alone( burnt orange is hot 🔥) or layered under my sweater I ’ m warm and toasty…looking good! Not sweaty in this wool top; comfort is sexy, ok! Grabbing more for stocking stuffers 😊
See Price in Cart
WAS: $60.00*
nike dri- fit technology moves sweat away from your skin for quicker evaporation, helping you stay dry and comfortable ... wear it on its own or as a base — either way, the soft and stretchy fabric feels comfortable on the skin and the tight fit makes it easy to layer
$90.00
Love the fit and breathability, a bit less wool and more synthetic than other brands I wear, but it works for me since this is a hiking base layer that I wear multiple times without washing- does n't get stretched out and dries
5
Gandhi
[ Bought for a hiking baselayer. Expensive but I think its worth it. More comfy in the cold than a synthetic baselayer. Not a compression shirt. I use under a fleece. Does n't smell after a full day of hiking.
5
Jackie28
[ This is my second purchase of a Smartwool Men's Classic All- Season Merino LS Base Layer- this is a great lighter weight item that breathes well but is warm enough when it gets cooler.
5
Rover Dog
[ I own several Smartwool tops but this is one of my favorites. The slightly heavier material is ideal for stand alone yet still layers nicely. Never bulky. Quality is what you would expect from Smartwool. Excellent.
5
Tony99
[ I have tried more than one brand of merino tops Keep coming back to smart wool for best quality and fit. They also keep their shape. The price is inline with other brands
5
Thunderbolt417
[ I 've long been an unabashed devotee of all Smartwool products but their base layers, like the classic all- season merino long sleeve shirt, is truly the best money can buy. Since my days of living in the frigid mountains of northern Utah, I 've discovered the breathability of Smartwool's all- season merino long sleeve base layer makes it both the perfect shirt for keeping warm on winter's coldest days as well as ideal workout apparel. Smartwool base layers also make the best all- season pajamas imaginable. The all- season merino long sleeve shirt feels like a gentle hug when you slip it on, and remains comfortable until you 've completed your workout — whether it be a 3- mile hike in the frigid cold or a home gym weight training session. Smartwool has long been the gold standard for merino wool apparel. When you purchase your first Smartwool product, you 'll understand why.
$115.00
slim fit 100% merino wool fabric made with an interlock knit for enhanced comfort, breathability, thermoregulation, and odor resistance fit updated to improve functionality while enhancing aesthetics for a range of body shapes back body seam wraps to front for body- enhancing fit crew neck with...
5
BGRD
[ This shirt is incredible. I wear them daily during the winter time so I wanted multiple. Smart wool shirts are warm and not itchy at all! I wear them hiking as well as under dressy tops to stay warm in the office.
5
reddread
[ I waited forever to get this on sale and now I wished I 'd bought several in different colors! Warm but breathable, and stylish enough to layer with a jacket for a business casual look. I ca n't wait to take this baby out to the slopes!
5
Beez
[ SmartWool is our go- to for liners. It's well fit, cozy, soft and super warm. It does n't itch and make you warm yet is great to wear inside and on mild days out. Got this one for my wife.
5
klili
[ I got this a couple weeks ago and it's been perfect, it's of course a great base layer, but for days when too many layers are n't needed it is perfect as a long sleeve T- shirt. Hoping to get a couple more to round out the winter layers
5
Springtime44
[ I love smartwool products! This is my second of this specific shirt! My first one was a medium, which is perfect for layering, very form fitting. So I purchased a second in a different color in a large to wear everyday!
$120.00
slim fit baselayer top fit updated to improve functionality while enhancing aesthetics for a range of body shapes classic, comfortable crewneck design raglan sleeves achieve added comfort back body seam wraps to front for body- enhancing fit shoulder panels eliminate top shoulder seams flatlock...
5
JaniceN
[ I bought this about a month ago in black and Heather gray. I do miles of outdoor walking every day and need a base layer for walking in the winter in Vermont. This works well as a first layer a shirt and my down jacket. Washed well in cold water, hang on a hanger to dry.
5
sof2024
[ This is my go- to base layer for skiing( or any other outdoor cardio activity... if I ever did one). It's form fitting and has great mobility. I always use merino fabric as my base layer since it's' breathable and odor- resistant. This top kept me warm but not overheated in 30 degree weather with a down ski jacket. I prefer to minimize my layers so this top paired with my jacket is all I need in everything but extremely cold or warm skiing weather. It's also stylish and looks good with ski pants on its own for apres!
5
Cutie
[ I love smartwool classic( midweight) baselayers. Live in Ohio where it's freezing winters and these tops work great as a baselayer or a stand alone top. They are wool so they breathe and it dries quickly if it gets damp( Unlike cotton). I have multiple smartwool tops& love them all.
5
VermontWinter
[ I bought this as a present for my daughter. It ’s perfect as an under layer for skiing. I can always count on Smartwool for quality products. She loves it!
5
Dog mom
[ It got really cold last week- 16 degrees- and I was glad I had purchased this Smartwool merino thermal top. It kept me warm during an hour hike and the material is so soft and cozy. A perfect winter base layer.
$75.00
on its own or worn as a layer, this top has soft and stretchy fabric for a comfortable feel. ... made from recycled materials acg apparel is designed as a nesting system so you can adjust to your climate and activity level this product provides uva and uvb protection from the sun only in the areas...
$130.00
Great layer piece as well as a dress look under the Men's Intraknit™ Merino Sport Fleece Full Zip Hoodie. The hand and softness of this fabric brings Smartwool back into the top of the line
$31.97
WAS: $120.00*
running the streets day or night, solo or in a club, this top keeps you ready through it all – and after. ... designed with soft blended fabric that helps regulate your body heat and thumbholes that extend your coverage, you can feel comfortable as you pound the pavement into your next
$110.00
Love that something fits tall women, is functional, comfortable, and stylish. ... Love the fit- comfortable. ... Perfect and pretty base layer great for
$90.00
cut with a secure, tight fit, it's equally comfortable layered or worn on its own. ... not intended for use as personal protective equipment( ppe) ... fit& design tight fit offers a close cut through the body and sleeves flat- stitched seams give a smooth feel and a technical look...
$85.00
fit& design regular fit running top mock neck with 1/2 zip design long sleeves thumbholes let you extend your coverage and help hold the sleeves in place soft and stretchy poly- wool blend fabric has a waffle- like texture to help provide warmth and breathability technology nike...
5
3dyers
Love this half zip top! I know it ’s men ’s ’ but I ordered it in a small and it fits perfectly! Very comfortable material and lightweight, perfect for running errands! I wish there were some brighter color ways other than the light blue, but definitely thinking of getting the maroon one as well!
5
charlesp772116876
This thing is too good. Perfect for cool days with big climbs. Fully unzip and roll the sleeves up on the way up and then zip back up and roll the sleeves down for the way down.
$40.00
designed to be layered or worn alone, this long- sleeve base layer top is made of soft jersey knit fabric that uses our sweat- wicking tech to help you stay dry and
See Price in Cart
WAS: $90.00-$95.00*
a slim fit that tapers around the waist makes layering with other pieces easier thumbholes let you extend your coverage and help hold the sleeves in place a zip pocket on the left side seam fits items like earbuds, a key or a card reflective swoosh logo on left chest reflective graphics on sleeves...
$80.00
soft, comfortable and versatile for a wide variety of active pursuits cool- lite™- breathable and lightweight fabric blend designed to help keep you cool offset shoulder seams to prevent friction 360° reflective details eyelet mesh for ventilation and visual texture narrower armhole for a sportier...
5
Sarah G
This is the perfect tank for hot summer. I 've hiked and worked out in it and it's lightweight and breathable
5
Sal
[ After I bought one, I ran out and got another immediately I like it so much
5
VCS
[ This cropped boxy tank is perfect for hot run days!
4
Magnolia
[ I wear it under a long sleeve shirt for hiking in the summer. I got the white one, it is a little shear, but I love the cropped length. I wish icebreaker was written on the back rather than the front.
$59.99-$75.00
WAS: $75.00*
nike dri- fit technology wicks sweat away from your skin ... 1/2- zip design mesh panels underarm and inner collar provide extra breathability simplified shoulder design provides distraction- free movement thumbholes hold sleeves in place provides uva and uvb protection from the sun in the areas...
5
JakeMango
I bought this to run a half marathon in when it was like 40 degrees. It was warm enough that I didn ’ t get cold in the beginning and breathable enough to not overheat once I got a couple miles in.
5
Duncanson1990
This shirt is fantastic. It ’s basically just a much needed upgrade version of the 1/2 zip elements. What I mean by that is the material is soft and comfortable and stretchy. The shirt also has a mesh ’s area running on the bottom of the arm that goes along the whole sleeve which is nice to help with cooling off. Also it seems to be lighter than the elements which helps it be a better choice to wear on warmer days. Hope these stick around and get more colors. I definitely recommend these especially if you were a fan of the 1/2 zip elements.
5
BonafideHustler16
Superb from Nike. In truth I went off Nike running clothing for a bit- felt there were too many weird fits and not always best material, but this is a brilliant top. Great fit, great material, very comfortable and looks very good. Waiting for other colours before ordering another. If not I ’ ll get the black.
$60.00
nike dri- fit technology moves sweat away from your skin for quicker evaporation, helping you stay dry and comfortable provides uva and uvb protection from the sun only in the areas covered by the
$80.00
our lightest, most breathable performance tank featuring cool- lite™ eyelet mesh throughout, the merino 125 cool- lite™ speed short sleeve t- shirt is ideal for running and any other high- intensity pursuits in warm conditions cool- lite™- breathable and lightweight fabric blend...
5
Alex
[ I got two of these for daily undershirts. It is very comfortable and of excellent quality, a little baggier than expected.
$85.00
stay warm on those chilly morning runs in this top. ... nike therma- fit technology helps manage your body ’s natural heat to help keep you warm in cold- weather conditions thumbholes let you extend your coverage and help hold the sleeves in place while you move collar stretches to add face...
$55.00
Great base layer to use in the cold ... fitted long sleeve shirt for casual or athletic wear ergonomic design keeps seams off of high abrasion areas dropped, shaped hem dual- layer fabric with an ultra- warm, brushed interior& a smooth, fast- drying exterior...
5
RicoGerardo
Used this shirt under my winter jacket for a trip to Yellowstone and kept me warm throughout the day. Would highly recommend as an inner shell when out in the cold.
5
iony boy
excellent product higt quality
5
CaptDave13
I really like this shirt at the gym. It ’s very light and comfortable. Fits loose which is perfect when working out. I would recommend this shirt even for hanging out.
5
K Saucier
Bought for a trip to Alaska. It kept me warm the entire trip.
5
MamaToHayden
I purchased this for my boyfriend for Christmas and he loves it! He wears this for all his outdoor activities and he is never cold.
$55.00
This shirt is great for wearing as a base layer or on its own. ... Perfect base layer ... Perfect amount of warmth that can be layered as much or as little as
5
dmitch1989
used it for my sons baseball game kept me very warm good material
5
Roxtar
My daughter loves this when she plays golf and its cold
5
brother shoes
I wore this cold Gear due to our cold spring soccer games and it kept me warm.
5
Danielle Harris
The quality of product was great. The fit of item was accurate according to description.
5
Guido10
Daughter got this for her game in 22 degree weather and was good!
$120.00
slim fit intended to follow the contours of your body fabric helps combine the moisture management, temperature regulation, and odor resistance of 100% merino wool with interlock knit for comfort flatlock seam construction and offset shoulder and side seams designed to help increase comfort and...
$55.00
I normally wear a small, but bought XS because I like a base layer fairly snug. ... It would work great as a base layer for any occasion. ... Perfect to layer under field hockey or softball
5
Skorpio23
This fits true to size and is very comfortable. My Daughter loves if for those cold early spring softball games.
5
Suzie7
Perfect, the quality is amazing.. Really nice and good product, I love it..
5
Smus54
Purchased this for both my wife and daughter for when they coach and play softball, respectively. They ’ ve been pleased with how well it keeps them warm as well as the comfort.
5
chandanabells
We purchased this for my daughter to wear under her softball jersey to keep warm during cold spring games. She is a pitcher so she needed something that kept her warm but also was not constricting. This is exactly what we needed. My daughter said it was very comfortable and allowed her the freedom to move while playing softball. She also liked the neck line because she does n't like undershirts that are tight around the neck area.
5
kzdog
fits great and keeps me warm. would definitely purchase again.
$35.00
This is great as a base layer or even alone under a coat for winter activities. ... I wear this every day at practice and it ’s very durable ... She loves this thickness as it provides warmth but allows her great mobility and stretch to pitch
5
Anjetai
Super comfy, good quality, good price, I love it, buy it!
5
PESKADARU920
Great product, very comfortable.
5
Ez miller
Works great wife loves the fit and comfort breathable
5
Bgladys535
5
4444bdlb
My daughter uses this for underneath her uniforms for an extra layer of protection.
$14.97-$30.00
WAS: $30.00*
for backpacking, hiking, running, training ... It really wicks the sweat after a good gym session. ... It is actually very soft fabric and stretches nicely. ... I am loving this tee due to compression feature and ease of use and
5
Yellomellow
These compression shirts are nicely made and breathable. If you do not like a snug fit definitely size up!
5
Flame_Thrower
Bought this a month ago to keep me warmer during my softball game.
5
RJoshRod
Easy and quick purchase. The coolest thing was that I was in a hurry and 15 minutes away from the store. I got there five minutes before they closed. They kept the doors open for me and had my shirt packed and waiting for me. I really appreciate their patience.
5
Beck27pickup8
I bought this for my daughter for workouts and it fits just right( not too tight, not too loose).
5
AS76
Awesome for basketball undershirt.
$28.00
It ’s a great product for a base layer. ... The fabric is nothing short of fantastic. ... Fits well comfortable my daughter wears under jersey for basketball and loves
5
lsjdmteg
keeps my son cool umder his gear on hot days perfect fit
5
Boymomfootball
My son wears this for his sports and loves it! Keeps him cool and dry!
5
Yenifer12
Very nice quality and very good Comfort
5
boymom87
My boys love to wear headgear armour by Under Armour. It keeps them nice and warm and they are comfortable to wear against their skin.
5
vania017
My son loves this compression shirt! He said it is super soft, dries his sweat quickly and the sleeves and torso lengths are just right.
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