The next generation of our best-selling MicroTherm ultralight, this new jacket features FreeFuse construction. Traditionally, inner and outer layers of fabric are stitched together and then quilted with additional stitching. But this jacket is made with a single sheet of fabric that's folded over and woven together in discontinuous channels to hold the down. This cutting-edge technique saves weight, maximizes breathability, helps reduce cold spots, and minimizes down migration.The nylon/spandex stretch shell provides exceptional mobility and features a super-durable water-repellent finish that beads moisture. High-loft Premium Down insulation delivers sub-zero warmth in mere ounces.