The Marmot Quasar hoody is 900 fill goose down with a lightweight pertex quantum shell material. It is super light and packable but due to the high fill down gives phenomenal warmth. I have worn this as a summer alpine climbing insulated jacket, as a layering item for really cold days and it is always with me. The hood is great and fits under or over a helmet well. The jacket folds into its own pocket meaning you can clip it to your harness and start climbing! On a cold alpine climb last year a loaned this jacket to a client to keep him warm (all part of the service). He was so impressed that next time I saw him he also owned one. When deciding on clothing for a trip to the alps, in a couple of weeks, this will be the first item in my pack.