If you’ve ever shopped for a puffy jacket or sleeping bag, you may have seen the phrase “down fill power” in the product description. It’s a number, usually between 500 and 900, and it is a general ...

Down duvets and comforters — which are stuffed with down, the layer of fine, soft, and fluffy feathers underneath a duck or goose’s exterior feathers — have an airy, lofty feel while being warm and ...