Custom Down and Feather back cushions are made with 200 threat count downproof 100% cotton fabric. The cushion is chanelled into compartments to prevent the down and feathers from moving downwards. Keep in mind that this type of cushion is not flat, it bulges out in the center (the bulge is called a "crown") and also can require a bit a maintainance to get the wrinkles out after someone has used it. The size should be entered according to the size of the cushion case and we will add a few inches to each side for compression and for the crowning effect.