PATAGONIA MEN'S / WOMEN'S ULTRALIGHT DOWN JACKET
I can't preach about this jacket enough; it has changed my life.
I am a very warmblooded person and have grown accustom to believing that if I am warm outside in cold weather, I will overheat inside in a warm building. But thanks to this piece of gear? Never again. This jacket/hoody gives you the insulation and warmth of down but the breathability and ventilation of ultralight expedition gear. If I am cold, I zip it up. If I am hot I unzip it. It is literally the perfect layer—plus it will double as a pillow when you are backpacking.
Note: if you are planning to be in rain, opt for the Nano Puff jacket. It offers similar compressibility and warmth (perhaps even running a bit hotter) but with synthetic lining instead of down (which clumps and loses loft in wet conditions). —Jesse Lenz