Down fill

"Down fill" refers to the type of insulation used in outdoor gear, such as sleeping bags and jackets, where down feathers are utilized to provide warmth. The term is often accompanied by a numerical value indicating the fill power (cuin), which measures the loft or fluffiness of the down. A higher fill power generally signifies better insulation properties. Down fill is favored for its excellent warmth-to-weight ratio, compressibility, and ability to provide effective insulation in cold conditions. Outdoor enthusiasts often consider the down fill when choosing gear, as it directly influences the product's thermal efficiency and overall performance in various weather conditions.