Here's what other sites are saying:
This is the layer to keep you fast on your feet without sacrificing protection from the elements as you run, bike or hike. About the weight of two energy bars, this vest is made of an innovative wind-blocking nylon fabric that's treated with a durable water-repellent finish to repel moisture. Still, it's incredibly breathable when you work up a sweat and stretches as you move. Scrunches down to about the size of an apple to fit in its own small pouch that tucks easily in a pocket. Full zip. Elasticized arm openings and hem. Two hand pockets with reflective detailing. Imported. Fit Slightly fitted; best with a lightweight layer.