Soft duck feathers are a type of down feather that come from the EIDER duck, which is a large sea duck native to the Arctic and North Atlantic regions. The EIDER duck is known for its soft, warm feathers, which are used in many products such as sleeping bags, pillows, and comforters. The feathers are also used in fly-tying and other crafts. Soft duck feathers are highly sought after for their warmth and comfort.