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  • Soft, nonirritating merino wool offers lightweight warmth next to skin and resists odors naturally
  • Lightweight merino wool wicks away moisture, dries quickly and breathes well to regulate temperature for outstanding warmth in cool weather
  • Fabric offers protection from UV light with a rating of UPF 50+
  • Flatlock seams reduce chafing, and offset shoulder seams will not rub under backpack straps
  • Machine washable; line dry or dry flat in shade
  • The women's Icebreaker Oasis half-zip long underwear top has a slim fit


View all Icebreaker Women's Long Underwear Tops

REI membership


Best Use Snowsports
Shirt Style Zip-front
Fabric Merino wool
Sun-Protective Fabric Yes
UPF Rating 50
Moisture Wicking Yes
Quick Drying Yes
Underwear Weight Lightweight
Sleeve Length Long Sleeve
Gender Women's

Size chart

Sizing notes

Measurements are stated in inches unless otherwise indicated. CHOOSING THE RIGHT SIZE: If your body measurements are midway between two sizes, select the smaller size for a tighter fit or the larger size for a looser fit. If your body measurements result in different sizes, we recommend using your chest measurement for tops and your hip measurement for pants.

Rated 4 out of 5 by from Love the top but don't like being a walking advert I live in Icebreaker products for most of the year but I have to say I'm Not impressed by the obtrusive, bright white "rubber" Icebreaker logo on the shoulder area of the left sleeve of my new Oasis long sleeve half zip. I ordered on-line and it wasn't visible in the picture or I wouldn't have purchased it. Otherwise it is exactly what I wanted, so I am disappointed that this non-essential detail makes the top less versatile and so conspicuously sportswear that I can't also wear it on a more formal occasion as I normally might.
Date published: 2013-10-18
Rated 5 out of 5 by from The Morning Commute I commute downtown to work everyday and this is the perfect layer for the early morning chill in the air. The sleeves have plenty of length and the 1/2 zip allows me adjust as I warm up on the ride. I am 5'8" & weigh 155 pounds so I bought a size large. It is still slim fitting but allows me to add a cute t-shirt underneath so I am good to go at the office. I have the light gray color so it teams well with black or blue jeans. I love how I can stuff it in my backpack, taking up very little room, then pop it back on when the weather invites me to with that winter chill.
Date published: 2013-10-21
Rated 5 out of 5 by from Thin yet keeps me toasty This is a thin wool baselayer that keeps me toasty while being stylish. It is soft and not itchy. I usually wear a medium in Icebreaker and found it true to size. The neck zipper is fully lined on the back - so no irritation against my neck. There is a logo printed on the left bicep which keeps this a strictly casual piece, but I love the way I can sweat in it without being stinky. I use it as a baselayer for cross country skiing under a fleece vest and light windproof jacket and I have to admit that I like this top so much I used it as a pj top in my chilly winter house.
Date published: 2014-03-08
Rated 5 out of 5 by from A shirt for almost any occasion! This shirt is my new favorite piece. Lightweight and super soft. I am 5'7" 115 lbs with a 34 A bust, Small fits really well without being restrictive. XS fits fine too, but I prefer a little room. I have worn this running, bouldering , hiking and even paired it with a skirt and boots and wore it to work. So versatile, just what I like in a piece of clothing.
Date published: 2013-11-05
Rated 4 out of 5 by from Nice shirt, very fitted I usually run between a small and extra-small in Icebreaker (5'5, 118 lbs) depending on how fitted I want the item. For base layers I often go with xs but this was very fitted. I probably would have exchanged it for the small, since I like the color and style but I was not crazy about the large Icebreaker logo on the shoulder, so I returned it. I like my clothing to be versatile, and the logo gives this top too sporty a look. Plus I'd really rather not be a walking advert.
Date published: 2013-12-03
Rated 4 out of 5 by from Versatile shirt - hiking,walking, riding I ordered this shirt years ago and wear it so much, due to comfort and style, that my old shirt has a few holes. I reordered this shirt and although the comfort level is the same I do NOT like the printed logo on the sleeve. When possible I always remove exterior labels from my clothing but that is not possible in this case.
Date published: 2014-02-01
Rated 4 out of 5 by from Great and versatile base Layer ! I am 5.1 and weight 95 lbs. I Ordered the XS. Fits great. Slim shape. I wear it directly on the skin or over an icebreaker T-shirt. The sweater is Quality made. It stretchs a little bit as you are wearing it.. but not enough to get a bigger size. It's so versatile. I bought the grey one and it goes with everything :) It's very comfortable.. I wear this sweater all the time for everything. ( gym, hiking, shopping etc ). It dries quickly and I don't sweat as much in this sweater compared to other base layers. It doesn't smell, it's a great item for every season. I am thinking about buying an other one:)
Date published: 2017-05-22
Rated 5 out of 5 by from Great shirt; wish I bought more! I read a review of Icebreakers in a Sierra Club mag…from last year, and ordered a few things as gifts & for me. I love this shirt. I've worn it 4 times and it doesn't smell yet. I'm finally washing it today so we'll see how that goes. The fit is great. Just snug enough, and enough stretch to move comfortable. I love the color too. (green)
Date published: 2013-12-15
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