This is the new version of the former popular Proton Lightweight Hoody and the former Proton FL Hoody that has been updated with an insulated hood, more durable fabric, and a revised chest pocket and design lines.  An air permeable insulated softshell jacket from Arc'teryx designed for summer alpine and rock climbing, hiking, and running.  Active insulation layers like these are designed to maximize breathability in cooler conditions to keep you comfortable though a broad range of temperatures and activity levels. This jacket represents the 3-way intersection of something like an lightweight softshell jacket, a lightweight synthethic fleece mid-layer, and a superlight synthetic puffy jacket all in one.  The Octa® Loft knit insulation provides warmth while allowing airflow to regulate temperature.  The outer fabric is stretchy and fairly abrasion resistant, and is moderately wind resistant while allowing some temperature-regulating airflow.  You will end up using this for many different activities, and it will likely become one of your favorite pieces to wear around every day because it is so comfortable to have on.