Survival is my witness. Survival in -60 ° f says alot for any goose down. Unless you are measuring snowfall by the thimble and the goose down by the days and months in that hostile temperature, rate them all the same unless the African goose, for example only, cannot prevent one from perishing in this hardship. Oscar Myer once had a hot dog commercial : " My dog's bigger than your dog" it was nonsense of course and would not mention the Foot long Coney Island Beef dog.

If my goose down is warmer than your goose down, it needs to prevent me from perishing in "forty below" temps. Which any goose down should. If my goose down is warmer than yours in temps crazier than that, you should invest in a moon suit.

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My answer is: goose down was and is known as "Goose Down" not "Emdon down" or "Afro-gray". My sleeping bag in the artic was " goose down" from Army/Navy store did Uncle Sam buy only the best goosedown if there is any? ( not likely)