I'm 5'8", 160 lbs, 38 in. chest. I used to own the Skyward 1 in size medium, which was perfect because the fit was good while allowing room for layers (I returned the jacket after 1 season due to snap and zipper failures). For this Skyward 2, I ordered sizes Sm and Md and ended up keeping the small, because the Md's and the sleeves were way too long. Unfortunately the Sm is quite adjusted now, but the fabric's super stretchiness should make up for it. Bottom line is, size down if you're in between sizes like me, but be advised that this jacket has very little room in the armpit area. Ascentshell's stretch and breathability are awesome. The full lenght side zippers and bidirectional front zipper are key for ventilation, I absolutely love these features for skinning in wet, variable weather. I also like the cuff straps that can act as thumb loop if needed. I don't like the new hood design with "hoodlock". The old hood worked perfectly fine without a helmet, the new one not so much.