Seat Cushion: Hollow design, breathable and relaxed buttocks, fit the curve of the buttocks, more comfortable to sit for a long time Inflatable Donut Cushion: Distributes your weight evenly and reduces while sitting.Seat Cushion with good air tightness,easy to use and store Material: Waterproof material,soft, comfortable, durable, easy to clean Description: Size: 45.5cmx39cmx11cm/17.91 x15.35 x4.33 inch