The Women's Arc'teryx Proton Hoodie Jacket is an insulated jacket for staying comfortable during high-output mountain activity. Lightweight and toasty thanks to Coreloft Compact 80g insulation, it provides heat in the cold and breathes when your body heat rises. The shell fabric stretches for movement and provides light weather resistance. This fitted jacket hugs the body so it won't get in the way of necessary gear, and allows room for layers under and over.