"The Patagonia R1 Air Zip-Neck Fleece is the pullover cut of the R1 Air line, built for aerobic output where a full zip adds more than necessary. The slim fit and hip length keep it locked in place through sustained movement, so it stays tucked and out of the way from the first switchback to the last. What Our Gearhead® Experts Are Saying:""I wear this on hard uphill days when a full zip would just be in the way. The zip-neck vents fast when I need it and seals back down without fuss."""