Why are down jackets one by one or one by one?

The reason why down jackets are segmented and divided is to fix down. Only when down can be evenly distributed on the body surface can it play a better role in keeping warm.

Think about it, if there is no Fang Gezi and a whole feather runs under it, then every feather should have a grid. There is a calculation of gram weight when filling down, and each grid should be filled evenly. Generally, clothes are filled more on the top than on the bottom.

Clothes can keep warm, because still air can insulate heat. In winter, the fabric with thick clothes and compact structure blocks the air flow inside and outside the clothes, which reduces the air exchange speed between the inside of the clothes and the outside, thus greatly weakening the external heat conduction of human body temperature and improving the warmth retention.

Down jacket is also based on this principle. Down is composed of feathers and down. Feathers are small spines that grow on the back and tail of ducks or geese. Velvet antler grows in the abdomen of ducks or geese, and has a three-dimensional dendritic structure, consisting of a velvet core and many radial velvet filaments.

Wool has many small holes to store still air. The heat conduction of these still air is low, which forms a natural barrier to the flow of cold and hot air.

This structural feature also makes down feel fluffy and accumulates a lot of still air. In addition, the surface of down jacket is mostly made of fabric with compact structure, and the fluffy down distributed between them makes the whole down jacket surface bulge.