Our luxurious pillow inserts are crafted from soft, full 7D virgin fiber and treated with silicon to prevent clumping. These American-made cotton shelled polyester fiber pillow forms are the perfect balance of softness and firmness, free of odors, lint, dust, and free from any flame retardant chemicals. The high-thread-count cotton shell (not removable) is constructed with a built-in safety stitch to keep it from unraveling in the wash. Available in many sizes. See below for sizing information. Sizing: For pillow cover sizes 18x18 or bigger, you will need an insert that is 2 inches larger (Example: 18x18 will need 20x20 insert) For pillow covers smaller than 18x18, you will need an insert 1 inch larger (Example: 16x16 inch cover will need 17x17 inch insert). For lumbar sizes such as 12x20, add one inch to each side to determine the insert size. (A 12x20 inch cover will need a 13x21 inch insert)