How to Choose Base Layers

Ideal for year-round use in traveling, hiking or relaxing after a big day outside, the Icebreaker Siren Sweetheart top is soft and stretchy with an updated fit and fabric that make it even more comfy.
Imported.
View all Icebreaker Women's Base Layer Tops| Best Use | Casual |
|---|---|
| Shirt Type | T-shirt |
| Fabric | 83% merino wool/12% nylon/5% Lycra spandex |
| Moisture Wicking | Yes |
| Underwear Weight | Lightweight |
| Sleeve Length | Long Sleeve |
| Gender | Women's |
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I love this shirt!! I honestly have been wearing it almost every day this winter. Perfect for hiking or just an everyday shirt to keep you warmer. Stylish and comfortable! I ordered XS I'm about 5'4' 115 pounds
For years I wore uniqlo heat tech shirts, but those would get sweaty and stretch out over time, and I would get too hot in them. This shirt is much nicer on the skin as it never made me sweaty and stays fresh for much longer. I lost my shirt and was devestated—and have since bought a new one. I like that the cut of these shirts are low enough that they’re usually not visible underneath other items, and if I do end up taking a layer off I think the neckline is really beautiful and flattering. I do wish the shirts were a bit longer so they could stay tucked in better. I bought a size small (my usual size, with a chest size of 34b) and it fits well, fitted without being tight.
[This review was collected as part of a promotion.]
[This review was collected as part of a promotion.] I really love the weight and warmth of this top and have two others in different colours. Would buy more of them if there were more colours. Perfect to put in a bag as it folds very small so handy extra layer even in a small handbag or on a flight.
The neckline is pretty wide open and the body fits close. I got my usual size medium, and it's very close-fitting though not tight. It feels a bit itchier than the Icebreaker merino 200 oasis crewneck.
[This review was collected as part of a promotion.] A lovely top -with a good boat neck so yu can wear it under tops without it showing. Only downside is horrid scratchy label sewn in to side. Had to undo seam to remove it and then sew it up again.
This came in a box labeled "underwear". As such, it would be fine but NOT as a long sleeved t-shirt as it is way too see through. Such a shame as it is a lovely colour and fit.
[This review was collected as part of a promotion.] A gift for my partner. We have been wearing Icebreaker for years. This is a great looking top with a feminine cut.
[This review was collected as part of a promotion.] The top is neat, comfortable and keeps me warm. I use it under normal clothes on very cold days.


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