Somewhat similar to the Arcteryx Atom line, best equivalent/comparison I can think of in terms of construction. PCU equivalent according to Beyond is Level 3, probably 3A, more of an active insulation. Stops the wind since it's all nylon shell and there's some good quality synthetic insulation inside, but it's definitely thin so not a jacket to keep you warm when the mercury really drops. Good as an outer layer just for a cool breeze, does alright as a mid-layer too, ideal in spring/autumn.