Living on the water in Downeast Maine, we experience the whole range of weather, including extended sub-zero stretches in the winter. Dramatic shifts can happen in a single day. The Nightsky vest is perfect for eliminating having to think about fitting in with whatever the environment might do. Compared to most "puffer" vests (synthetic or down) it is lighter, thinner, and beautifully cut so you're not surrounded by volume. It provides surprising warmth, but does not get hot if the temperature goes up. It's a terrific layer for really cold days; I can throw on a down/synthetic puffer jacket (such as my light, old Patagonia Nano-Puff jacket) and be comfortable in single-digit temperatures. I like the baseball collar way more than the usual stand-up collars (good on a jacket, just weird on a vest) and even the armholes have a noticeably better fit. IMO, the Nightsky color is particularly fine, way more attractive than plain ol' black or any of the blues that are common. It's rare to find any manufactured item in which every element of design and fabrication have come out right. This vest is one of those things. It's sure worth way more than its modest price tag.