Icebreaker Women's Siren LS Sweetheart Top - Mountain Steals
Icebreaker Women's Siren LS Sweetheart Top
Gritstone Heather

Women's Siren LS Sweetheart Top

Icebreaker Women's Siren LS Sweetheart Top is rated 4.6 out of 5 by 185.
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4.6 Star Rating
$50.99 - $85.00
up to 40% off
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The Icebreaker Women's Siren LS Sweetheart Top is a women's baselayer top that has corespun fabric for enhanced durability. The sleek design makes it good for everyday use and layering with other pieces we sell on Moosejaw. The sweetheart neckline adds an additional touch of femininity (and makes for better tan lines in our opinion).

Products on Sale are Discontinued Styles or Colors.

Product Description
Item No.   10303169

FEATURES of the Icebreaker Women's Siren Long Sleeve Sweetheart Top

  • Updated with improved fit plus corespun fabric for enhanced durability
  • Sleek design for everyday comfort and layering
  • Feminine sweetheart neckline
  • Icebreaker tonal screenprint logo
  • Durable merino blend regulates body temperature in all weather conditions

Fabric Details

  • 83% Wool, 12% Nylon, 5% Elastane

Product Specifications
Primary Fabric: Merino Wool
Features: Packable, Sun Protective, Quick Drying
Sustainability: Animal Friendly, Eco-friendly
Fabric Weight: 4.42 oz / Square Yard
Disclaimer: We only ship this brand to US Addresses.
Gender: Womens
Best Use: Casual
Fit Type: Slim Fit
Sleeve Length: Long Sleeve
Shirt Style: V-Neck
Product Reviews
Rated 5 out of 5 by from great for daily wear during quarantine I stocked up on siren shirts for quarantine. They are super easy and comfortable to wear around the house but still look professional enough to be on video. I can get multiple uses out of them before I need to put them in the wash due to the breathability and antimicrobial properties. I am 5'6" and 115 lbs and normally wear an XS in icebreaker and all other brands. I ordered a tank, t-shirt and long-sleeve in the siren series and had to size up to a Small for all of them. I'm glad I did though, because I love these shirts! I recommend the grey and lilac purple colors. I was not a fan of the white - it's very sheer!
Date published: 2020-07-10
Rated 5 out of 5 by from This top survived Zion and long shifts in the ICU Bought this top to serve double duty as a lightweight base layer for camping during the Texas winters and under Scrubs during a 12-hr shift in the Trauma ICU. I also wore it as a primary layer for a week in Zion during the winter! love it. Keeps me at just the right temp, layers well with other Icebreaker products, doesn’t stink after some strenuous hikes or an adrenaline spiking code in the ICU. Dries quickly, soft and super cute. I actually have 3 tops now and I get lots of compliments from co-workers and camping buddies alike!
Date published: 2018-01-27
Rated 4 out of 5 by from Best Lower Neckline Thermal Top Me: 5'4" / 135 lbs / 32DD / 35" bust / 29" waist. I got both the small and the medium as I was between sizes. My goal was a long sleeve base layer without a lot of fabric on my chest. (As an asthmatic I'm weird about tight-fitting necklines up against my neck or collarbones.) Small is too small; limits mobility. The medium has a nice cut (low-ish neck) that is snug against the bust, loose but not baggy against the ribs and waist, and snuggish at the belly and hips. Very long and nearly covers my whole butt. Note that it's an "ultralight 150" and only 83% wool. Not quite as cozy or as stretchy / loose as the Everyday Longsleeve Scoop Thermal Top in the same size. The Siren definitely runs smaller, so you may size up from what you would wear in the Oasis or the Everyday. (If the 175 Everyday were also offered in a sweetheart neck like the Siren, it would be the clear champion of thermal tops in my book, but since it isn't, the Siren isn't a bad compromise.)
Date published: 2020-10-01
Rated 3 out of 5 by from Disappointed I've been buying these shirts for years - I get cold easily and wear them under long sleeve shirts for extra warmth without bulk. I have two that I rotate through and wear almost daily to work and on weekends in the winter months. My last two I had for over two years, but they were getting worn and had started developing holes, so I purchased two replacement shirts. I am so disappointed as the quality has noticeably gone down. I used to wear these multiple times before washing them and they would never hold odor, but these new ones seem to retain any and all smells. Maybe you think my wash habits are gross, but wool is not supposed to hold on to odor - that's part of the point of it. Additionally, one of the shirts has developed holes after only a few weeks of wear! It took TWO YEARS previously for any holes to appear. I'm really bummed because these shirts are not cheap and I'm beyond the point where I can return them. I will very likely purchase additional base layers (from another company) unfortunately.
Date published: 2019-12-13
Rated 4 out of 5 by from Slightly itchy This was my first all-wool shirt, so it may be that I'm still a tad sensitive to the feeling of wool. I wore this under a sweater to a business meeting the other day because I knew the room would be very cold. I was impressed at the warmth the top provided, but I found myself occasionally itching myself. Other than that the cut is nice and can be worn as a casual shirt. I'm 5'4, 111 pounds and got the extra small. It's a tad tighter than I'd like to wear casually, but as a layer piece or for outdoor use the fit is fine.
Date published: 2017-02-09
Rated 5 out of 5 by from Keeps me warm I wear this shirt under almost everything I wear in the winter, including dresses. I'm a very senior citizen and am cold when everyone else thinks the temperature is fine. The sweetheart neckline is low enough to wear under open collar garments. In the summer, I wear the IceBreaker camis. I toss my IceBreakers in the wash and hang to dry. They travel well and are dry by the next morning. I like the "Snow" color and hope this color is continued. It might not be a young person's color but we seniors are active too and it's a good "underwear" color. A word of warning: I live in the U.S. and normally purchase a size small (LL Bean, Lands End). My first IceBreakers were a medium but I've now gone to a size large. I'm 5'5" and 122 pounds and small busted. The garment is a bit long in length & sleeves but it's not a problem. If it were, I'd get out the needle and thread. My only complaint is the price. Gosh, it's really expensive but I do love my IceBreakers!
Date published: 2018-05-31
Rated 5 out of 5 by from Perfect Baselayer for everyday [This review was collected as part of a promotion.] I love these shirts and own about 5 of them! They're so soft and comfortable and I can wear them several times before I need to wash them. I love wearing them under sweaters or even on their own! 5'7" 34C, 132lbs and I wear Medium in all the Siren line. I wear a small in icebreaker non-siren tops (Oasis top, tshirts, quarter zip, etc) but to get the same fit in the Siren tops I have to size up or it's skin tight. Buy these you won't regret it!
Date published: 2022-02-22
Rated 3 out of 5 by from Not so soft This is my first Icebreaker purchase. I heard of the brand after a cross-country skiing weekend and decided to check it out. The product is described as "made with our corespun fabric, soft merino wool fibers wrapped around a nylon core for added strength and durability, while retaining next-to-skin softness". To me, it feels somewhat prickly itchy, but tolerable when not perspiring. I can't wear regular wool products and this is much better, but I can't go so far as to say that I think it feels "comfortable" or invest in additional pieces.
Date published: 2018-03-01
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Size Guide

Icebreaker Womens Base Layers

SIZE X-Small Small Medium Large X-Large
Bust 30 - 32" 32 - 34" 34 - 37" 37 - 40" 40 - 42"
Arm Length 30.25 - 30.5" 30.05 - 30.75" 30.75 - 31" 31 - 31.25" 31.25 - 31.5"
Waist 24 - 26" 26 - 22" 28 - 30" 30 - 32" 32 - 35"
Hip 34 - 36" 36 - 38" 38 - 40" 40 - 42" 42 - 44"

Chest / Bust: Measure around the fullest part of the chest, keeping the tape parallel to the floor.

Waist: Measure around the narrowest point, keeping the tape parallel to the floor.

Hip: Stand with feet together and measure around the fullest point of the hip, keeping the tape parallel to the floor.

Arm Length: Measure from shoulder (Humerus) to wrist.

SLIM FIT: A snug, close-to-body fit for low bulk layering.

REGULAR FIT: Neither snug or loose. These garments can be worn solo or over other layers.

RELAXED FIT: Loose fitting lightweight layers.