Brian H.wrote a review of Arc'teryx Zeta AR Jacket - Men's on May 4, 2017
Familiarity: I've used it several times
Fit: True to size
I've been wearing this jacket for casual events and the morning commute to work at temperature between 30 to low 50's layered with Atom LT or a thin vest. I have to say it's comfortable to wear and the snug fit kept me warm from the wet and breezy days. The pit zip helps to regulate the internal temperature pretty well. The actual Sangria color is outstanding. It's between bright and dark red and it's perfect to pair with my dark dress pants.
Regarding the fitment. I'm 5'11, 185 lbs and ordered a Medium. It fits just right with a medium Atom LT. If you happen to wear just a t-shirt underneath, definitely there will be a bit of empty space. However, thanks to the draw cords, they keep the jacket stylish and functional.
Finally, a special shout-out to Austin @ BC. He take a good care of a picky customer like me.