Before Russia, China, Greenland, America... there was Beringia. The original story.
As light as "air" [Küki in Japanese] at 172g/6oz (size M) and packs down into the size of a water bottle. Designed primarily to serve two purposes; as a stand-alone “sweater” when lightweight and packability is the goal such as long distance & duration runs/hikes/bikes and as a perfect mid-layer under a shell when a normal puffer/down jacket is too much.
A full length center zip (two-way) provides many ventilation options.