This piece from Mammut is awesome. It is super warm and wicks moisture really well. Since we don't have any snow in the Wasatch so far, I have been using it for winter running. For high aerobic activities it is super hot. I look forward to using it for some ice/alpine climbing. I also think it would be great for resort skiing.

The fit is probably great for someone not shaped like me. I am 5'8 and 155lbs. My belly is the product of a summer spent rowing a drift boat around and crushing beer. This top clings in all the wrong places and I find the armpits a bit tight. In a size medium the arm length is nice, but the torso is tight. Maybe after a few months touring and ice climbing the fit will be better, but for now i'm not thrilled about walking around the ski lodge in this thing. If you look more like Ryan Reynolds you just found your new Tech Baselayer.

Excited to try this out once the temps drop and the snow and ice seasons get going a bit more.

Great performance top, great colors; love Mammut and great purchases in the past have instilled alot of confidence in this brand, but not sure what's going on with the PIT-FIT.... Even when in between sizing and tried both going up and down a size, both have issues with a very tight arm-pit opening which translates into an annoying fit and some constriction...and this applies to an athletic, medium, average build. Medium would have been better than large, but couldn't make arm/shoulders work. Even being fit and trim didn't help the sizing of this armpit cut. A little design tweek there and this top will be absolutely amazing in every way. Past versions of this top didn't seem to have this issue. Missing that last STAR because the pit size was a deal-breaker, unfortunately. Note: feedback is from a long-time fan and user of Mammut, male, 5'11" 170lbs

So I'll start by saying, this was an awesome fleece with a ton of thought put into the construction and design of this. It was a really nice piece that would be perfect for layering with for skiing, touring, ice climbing, mountaineering, etc.

My Sizing:
Only main downside with this was the Large seemed really small. In American brands, I'm typically a medium (current North Face apparel) or a Large. But the issue is when I go for Mediums, the shoulders are too tight and then with Larges, the waist is super loose and huge, but fits in the shoulders. This is where European brands have worked great since the Euro-Larges tend to fit me perfectly. I've got a few fleeces and jackets in Large from other Euro brands that fit perfectly.

Mammut Moench Advanced Top Sizing:
This thing is definitely slim. I felt like a fat kid with out tight it was in spot and how constricting it was. The shoulders were super tight in this. And when looking at the sizing chart, with a 42.5" chest, I'm technically a XL based on that but my waist at 33" is a Medium.

Midweight:
It didn't feel as thick as other midweight fleeces but was definitely a warm fleece that is super nice.

Slim Fit:
If you're a person with a slim build, I could see this being a great item to go for and get.

My Sizing:
Height: 6'
Weight 180-185lbs
Chest: 42.5"
Waist: 32-33" (depending on brand)
Jacket Size: M or L (depending on brand)

Like anything Mammut, this piece is incredibly well thought out and designed for with specific use in mind. The first thing I noticed wearing it around the house was how warm it was, even for a midweight fleece. Definitely great out on cold days climbing and likely ski touring, although I haven't had a chance to use it yet due to a lack of snow around Utah.

While, as the review below mine noted, the fit is slim and feels strange at first, one thing I noticed was that in wearing it around a bit, it stretched out slightly to accommodate my shoulders which felt tight at first. Similarly, even though the armpits felt snug at the beginning as well, they loosened up and I don't notice any places on the fleece that don't fit well anymore. Almost as if in wearing the piece it stretched just enough to fit me perfectly.

At 6'0 160lbs I would say it fits true to size as I went with a size L. But, if you want to wear anything underneath it other than a t-shirt, I would size up!

The materials and overall design of the shirt are quite nice. It seems like they added lighter material to all the hot spots where i get sweaty and hot the most and the thumb holes seem to be well laid out. I have always been a big fan of mammut's products. This shirt however was designed super weird and despite the overall good design its completely ruined by the fit around the armpit area which is just way to high. Ive never felt a shirt before with armpits that were cut so high. I am a slender 5' 8" 155 lb lean male who either wears medium or small shirts typically. I bought this shirt in a medium since it was a slim fit and despite being skinny I couldn't even fit in the medium. The sleeves on the shirt are the right length, the over all length of the shirt is great but the armpits are just to high that they dig into my armpits and the bottom front of my chest very uncomfortably. I really wanted to like this. I dont know if i will try the large or not. If you buy this shirt definitely size up unless your a twig.