Winter down quilts are filled with about 180 to 220 gr.(5 to 8 oz.) of down per item and are usually made with an interior-partition system known as Kassetten.
The lower and top fabrics are not stitched together, but are joined by small bands between partitions, which act as walls. This quilt is filled, square-by-square, through a small hatch between the partitions. Once the process is finished, the hatch closes back to its initial position.
This is a very complex system that guarantees the non-existence of cold areas and for the down to reach the highest sponginess and volume levels, which succeed in offering an optimal thermic-isolation performance.