The "fill" dictates both the comfort and the "choppability"—the ability of a pillow to hold a crease when "karate-chopped" at the top for styling.
Sizing up by only 1 inch is often sufficient to prevent the pillow from becoming too stiff. how to buy pillow inserts
Throw Pillow Inserts, Pillow Forms & Pillow Cushions at WAWAK The "fill" dictates both the comfort and the