A down quilt is a quilt filled with down, which is light, soft and warm. The filling of a duvet is mainly down, which grows on the abdomens of geese and ducks into reed-flower-shaped down, which is called feathers in sheets. Since down is an animal protein fiber, it has higher thermal insulation than cotton (plant cellulose), and the down ball-shaped fiber is densely covered with tens of millions of small triangular pores, which can shrink and expand with changes in temperature, producing a temperature-regulating function. Absorbs the flowing heat emitted by the human body and blocks the intrusion of cold air from the outside.