Regarding the fit of the Ultra Light Jacket: 1. My chest (for bra fitting) measures 38" (size B cup). A 38" bra size fits comfortably snugly on me. This jacket for the 38" chest size, according to the size chart, is an XL, but I had an extra 1.5-2" material around my chest. The L size is recommended for a 36.5" chest, but it fits comfortably snug over my chest, which feels great, with no extra material left to be flapping in the breeze on descents. 2. I have broad shoulders, so though the jacket is not impossibly snug around my shoulders, it is snug, but still preferable to the extra material of the XL. 3. I have a 29" waist, and the size L is recommended for a size 31" waist and the XL is recommended for a 32.5" waist. L is definitely the better fit. 4. I have normal length arms in proportion to my torso length/ height. The arm length of the L just barely makes it. However, the XL arms are 1" too long. 5.. I am pear shaped, with wider hips (and shoulders). The widest part of my buttocks measures ~ 40" and on the XL, the material that extends over the widest part fits fine with even some room to spare. The size L, because it has a shorter length, fits comfortably snug higher on my waist. 6.. I am 5'9" tall, with a slightly longer than normal torso (but not a LONG torso). I really loved the extra 2-3" length of the XL jacket because it covers my bum almost all the way, while the size L leaves 2-3" of fabric exposed to the rain. 7. Typically I wear a women's size medium- large top. Overall the size L, even when tested with a warmer insulated layer underneath (as I usually wear coming down from chilly CO mountain passes, especially in the rain), fits comfortably snug and therefore won't flap heavily in the breeze on the descent as the XL will. So though I have a slight bit of snugness in the shoulders in the L, and though I really like the extra length of the XL, the L is the better overall aerodynamic fit. But I can tell I will love this jacket - so light and packable!