Your intensity on the trail constantly changes, and the baselayer compensates for that. It reliably wicks away sweat during steep climbs, so you don't catch yourself in a wet mess on the descent afterwards.

This mid-layer keeps you warm when you're in the shade or at altitude, while allowing moisture to escape. Its lightweight design means it won't add bulk under a running vest and can be easily packed away in your backpack when needed.

Insulation is your safety on the mountain. It keeps you warm as soon as you stop, wait, or the weather turns. Packed small, it belongs in your pack on long trails, even on days when you don't need it.

The top layer protects you from wind, rain, and cold in exposed areas. When trail running, it needs to do one thing above all: pack down small and be ready to go in seconds when you reach a ridge.

On the trail, your pants have to move with you every step of the way: the big stride uphill, the deep landing downhill, the crossing of scree. They keep your muscles warm, wick away moisture, and shouldn't chafe at the waistband and thighs, even after hours of hiking.