The bottom side of each bed liner has a layer of kapok sewn into individual channels to prevent clumping, provide a pillow of cushion for your pet and to maintain shape. Kapok, a fiber obtained from the seed pods of the Kapok tree, is an earth friendly alternative to cotton and like buckwheat hulls is grown without pesticides or herbicides and  harvested without damaging the environment. The buckwheat fill is added on top of the kapok, but sewn into a separate pillow. The buckwheat filling is light and flowing and moves with your pet to provide just the right support. Pets love to create a nest to sleep in and the buckwheat hulls allow them to move them around until the nest is just right. Plus, buckwheat hulls allow air to flow through the bed keeping your pet cool and dry, and unlike traditional foam or cedar filling, will last for years without clumping or breaking down.