A true Down jacket is any jacket made of Down, the layer of a bird’s feathers – normally duck or goose or both - which is found beneath the tough, outer feathers. Its primary advantage over other fill materials for jackets is its thermal properties and padding, or softness. The outer layer of a Down Jacket is made from polyester or nylon. Down is an ideal fill material for jackets because it is lightweight, fluffy, and has thousands of tiny air pockets which trap warm air and body heat.\r