The Cirrus Flex Jacket is a light synthetic insulated jacket, insulated with 3M Featherless insulation in a windproof Hyperlite ripstop shell. Underarm and side panels use Thermic stretch fleece for better breathability and movement. The trim cut and smooth shell means it layers nicely under a shell, but it's perfect on its own in slightly nicer weather. Cirrus Flex Jacket - Women's