Eric Stengleinwrote a review of Mammut Alyeska GTX Pro 3L Jacket - Men's on February 15, 2016
Familiarity: I've used it several times
Fit: True to size
This thing breathes. I was comfortable no matter what my exertion level was. While hiking to ski I left the jacket on and vented it out with main zips mostly open. Once at the top and in the wind I only had to zip everything up. My only complaint is the pit zips are hard to see and find, but work well once you get a hold of them. The fabric is slightly stretchy and soft which feels nice and is not loud when moving around. Pockets are plentiful. Wrist pocket on left sleeve is great for RFID pass and chapstick. Left chest pocket has a zippered pass through to get to the bib pocket. The main zipper goes to the side of the neck, which allows for more comfort when zipped all the way up. There is another zipper on the neck for a gusset which allows you to get the hood over the helmet without having to unzip the main zipper. Sometimes that zipper sneaks down a little. I really like the zip out powder skirt. The internal mesh pocket holds an iPhone 6S+ with ease. It packs down nicely for a full featured ski jacket. I'm really happy with the jacket.
I'm 5'10" with a muscular build. 44" chest. The XL gives room to layer without looking too long or baggy like the Trift jacket. This is what Mammut considers a "free ride" fit and is more loose than the other "regular" fit Mammut jackets I have. I appreciate the free ride fit as it allows for layering without restricting range of motion.