Despite often being mistaken for feathers, down is really the soft clusters underneath a goose’s feathers that insulate them in cold weather (who would have thought?). The lofted down filaments overlap and create small air pockets that trap warmth or body heat.
Wherever you find a down garment, you’ll usually find a fill number (such as 650-fill down or 800-fill down). Often mistaken for QUANTITY values, the fill rating actually indicates the QUALITY of the down within that jacket, sleeping bag, or what-have-you. Read More …
