- Down Fabric
A highly insulating material, unmatched by any synthetic material for its warmth-to-weight ratio.
Down consists of fluffy fibers and clusters of small feathers, commonly from ducks or geese. Down clusters provide the best insulation, so the lower the percentage of feathers, the higher the insulation quality.
Low priced down will have a down-to-feather ratio of about 60:40, while highest quality goose down will be about 96:4.
Even products labeled 100% down will contain some feathers. The insulation ability of down is expressed as its fill power rating.
My sleeping bag is made of down fabric, even though that term makes no sense.