The urethane foam cushion allows air and water to pass through, while the gentle curve gently cradles the body and disperses body pressure to the right extent. Excellent breathability reduces stuffiness when using, and is extremely easy to drain and drain when washing, reducing rinsing and drying. In addition, the moderate firmness and resilience force of the special nacurve shape firmly supports the body and pressures the body for excellent resilience and resistance to stiffness.