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  • Merino wool to help maintain comfort whether the climate is warm, cold or in-between
  • With a UPF 50+ rating, fabric provides excellent protection against harmful ultraviolet rays
  • Shoulder panels eliminate top shoulder seams, reduce chafing and optimize comfort under pack straps
  • Rear body seams wrap around to front to enhance fit, and sculpted side panels also enhance fit
  • Flatlock stitching eliminates abrasion, increases comfort and enhances fit by reducing bulky seams
  • The men's Smartwool Midweight Crew top does not itch and will not shrink; machine wash and dry


View all Smartwool Men's Long Underwear Tops

REI membership


Best Use Multisport
Shirt Style Crew
Fabric Merino wool
Sun-Protective Fabric Yes
UPF Rating 50
Moisture Wicking Yes
Underwear Weight Midweight
Sleeve Length Long Sleeve
Gender Men's

Size chart

Rated 5 out of 5 by from Don't want to take it off. I've had this top now for a couple of weeks and love it. I honestly had a hard time justifying the cost (even put it back on the shelf once before buying) but I am very happy with it. It hasn't been really cold here yet so I've been using it as a light sweater by itself (50 degree weather) and under a flannel (high 30s). Nice to be comfortably warm with no bulk. I wore it 3 days in a row doing various activities that caused me to sweat a lot - after 3 days no smell. Decided I'd better wash it anyway... I'm 6'3" 210 lbs and the XL is a perfect fit. Not skin tight like the picture shows, just a little room to move. I would highly recommend this to anyone!
Date published: 2016-11-09
Rated 5 out of 5 by from One of the best base layers... I have purchased LL Bean silk underlayer (discontinued I think), Carhartt, (very good also) but was lacking a Merino wool. I shopped around for while and found this at REI. Bought top and bottom, (not cheap) and prompty took it hunting in Colorado for the month of September. I wore the top and bottoms on a few ski trips. My impression, one of the best garments I own. It kept me warm hunting in cold, rain and snow. While skiing, barely noticed it on. Very good quality and it performs as advertised. i do baby it, wash by itself on gentle cycle and hang up to dry. I would buy another pair thinking I do not want to wear them out but not certain I will need to. 15 degrees, cold and snowy here today, think I will wear them :)
Date published: 2016-01-09
Rated 2 out of 5 by from Great shirt, bad durability I loved this shirt for the first week, I wore it constantly. Then on the second wash it start pilling badly, even after following washing directions. Now after 3 or 4 washes it doesn't even look like what I bought originally and it feels very different. It would have had full marks if it lasted a year, but it didn't last a month. Not good for such an expensive shirt.
Date published: 2015-12-29
Rated 5 out of 5 by from Love it. I bought both the mid crew and the light crew at the same time and the mid is definitely better for wearing as an absolute base. The mid is great at regulating heat, conserving heat, and making your warm clothes twice as warm as otherwise possible. I hated the ¼ zip because the zipper would always feel cold and the neck began stretching out after a few months. It always seemed kind of saggy as well. This must be a newer style of fit, and I love it. Very slim, but not to the point you couldn't put something else under it. Just a great, versitile option for colder weather activities. I practically live in mine (at least the mid bottoms) in the winter for 5 months out of the year or so. Smartwool, in my honest opinion, isn't quite as durable as other options you'll find cheaper. My older (2 seasons old) mid bottoms have developed some small holes in them and my Smartwool socks are wearing badly in the heel area. This leads me to believe that the material just doesn't hold up for a long period. Some people claim that it's expensive for what you get, but when you need the extra warmth or run cold, you'll be glad you paid the extra dollahs for the item when that time shows it's ugly head. I'd say gimme the wool, because when you run cold and are faced with cold won't be caring about the thirty bucks you could have saved.
Date published: 2013-12-05
Rated 5 out of 5 by from SMARTWOOL is AWESOME!!! I use as a base layer under a sweatshirt and I felt good in 38F. When I get into warmer environments the shirt does a great job regulating my body heat. I've been testing the wearability and I'm on my third day straight using this shirt as my base layer-NO odor, NO irritation! These shirts are definately worth the price.
Date published: 2012-11-06
Rated 5 out of 5 by from Wonderful! Bought one of these during the last sale and I wish I had purchased two of them. This wool shirt feels like cashmere, really. I can't stand typical wool against my skin. It is oversized so I moved from a large (41-42 chest) to medium, which fits perfectly. Long in the body for a secure tuck in and covers your wrist on the arms. I can't say anything about durability as I have only had it for 3-4 weeks; however, I've been using SmartWool socks for a long time and they are very durable. Kind of expensive but Smart Wool is a great product.
Date published: 2014-12-21
Rated 5 out of 5 by from Warmest Baselayer This midweight is warmer than similar synthetic heavyweights, and the SmartWool is better for odors. Perfect fit & construction. Strictly for winter, it will be too hot anytime you can simply layer on fleece & shell, but you can also strip down to this layer and be very warm.
Date published: 2014-03-21
Rated 5 out of 5 by from Fantastic product, exceeds my expectatio The only thing that could make this better is a thumb cuff similar to the Patagonia wool product. It is a tight fit but not overly so. Very comfortable and even at the price I am more than happy with my purchase and have actually gone back for more.
Date published: 2013-01-17
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Why don't you carry men's Tall size shirts? My husband wears a large Tall and that size is almost impossible to find, especially in the wool. There are plenty of XL and XXXL but he isn't a big person, just tall!

Asked by: cindybug56
We do carry tall sizes. Just type tall in the search box for all results. You can then narrow down the categories with the selections on the left panel.
Answered by: REIservice
Date published: 2016-12-25

How much does the Large size weigh?

Asked by: trail-rambler
The SmartWool Midweight Crew Top weighs 9 ounces.
Answered by: REIservice
Date published: 2015-09-20

What is the best wash care for the marino wool midweight tops and bottom? Thank you. Tom

Asked by: Tlcsfca56
Machine wash warm, gentle cycle, turn garment inside out. No bleach or fabric softener, tumble dry low. Cool iron when needed. For best appearance, flay flat to dry. Can be dry cleaned.
Answered by: REIservice
Date published: 2016-12-06

You describe Smartwool men's underwear as 150/195/250 and alternately as midweight, micro weight, etc. Is there a correlation between the numbers and the non numbered descriptions. Are they different or just different ways to describe the same product?

Asked by: santa rosa rabbi
Smartwool is in the process of changing their rating system for their baselayers from descriptions (micro-, light-, midweight) to a numbered system for consistency. 150 corresponds to microweight, 195 to lightweight, and 250 to midweight. The number refers to the fabric weight.
Answered by: REIservice
Date published: 2017-01-20
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