The Nike ACG Cloud Trekker Pants open up when the effort does. Zippered thigh vents with a mesh lining let heat escape mid-climb instead of building up under four-way stretch fabric built to move through every stride. Articulated seams keep that same mobility through a full range of motion, and a water-repellent finish sheds moisture in light rain and shifting mountain weather. An elastic waistband with a belt and a bungee hem dial in the fit as conditions change on the way up or down. What Our Gearhead(R) Experts Are Saying:"I unzipped both thigh vents halfway up a steep push and felt the heat dump almost immediately, without ever having to stop and strip a layer."