Our down jackets are filled with hypoallergenic synthetic fluff, which is the same as the natural one according to its frost resistance, and perhaps even surpasses it.
Coats blankets withstand up to -22 Fahrenheit (-30 degrees Celsius), but judging by the reviews of our customers from Siberia, they can withstand up to -49 Fahrenheit (-45 degrees Celsius), no one has ever frozen to death :)
In this synthetic fluff, unlike natural, do not live parasites, and it doesn't contain any animal allergens, as well.