This thing is amazing! I needed a light, small-when-packed down layer for backpacking and this is it. I have a First Ascent Guide jacket with 800 power fill for when it's just stupid cold out, but that was a bit bulky. The Kelvinator's hood and elastic makes it feel like a custom fit just for me. I was debating a jacket with a hood, but I'm glad I got this because it's just so much more convenient and warmer when standing around in the wind. I layer a Marmot Tamarack (awesome) jacket over this, and can even tuck the hood down and out of the way if I want to only use the hood on my shell. I don't notice it's there, plus it's like a built-in neck gaiter for the back of my neck. Just too much good to say about it. Stole one online for 142.95!!! Very difficult sizing. I'm 5'9", 150lbs, no gut. The small and medium were close, but I finally chose the medium since the small jacket dug into my arm pits - uncomfortable with layers on. Other than that, the sizing was almost identical. My cold winter, "standing around" setup is a Capilene 3 half-zip, 200wt fleece jacket, plus this = cozy blast furnace!