Gaping underarm zippers help move air through the jacket. Even as my brow dripped with sweat, my torso remained relatively dry and happy. And that pocket unzips from the bottom up, meaning you risk losing its contents if you're not zipper-conscious. Huge underarm zippers ventilate enough to leave you feeling fresh, even while grinding up a rainy slope. All this, and it weighs only 23 ounces.
Underarm vents are plenty generous, and they seal with waterproof zippers.
Hey, if you're gonna spend this much for a jacket, you should be able to wear it in Yosemite and San Fran alike. A nice trim cut means the Neutron won't look out of place around town. Sierra Designs has managed a streamlined fit that doesn't mimic a straitjacket. Vents extend from just below the underarm clear down to the wrist, circulating enough air to discourage moisture buildup. Extras include a large zippered inside pocket, two zippered chest pockets, and a size-adjustable hood with generous bill.