Superior Memory Foam. As prolonged sitting increases tailbone pressure, this chair cushion uses superior memory foam, which better responds to your body heat, evenly distributes weight and relieves your tailbone pain and spinal pain. Waterproof & Breathable. Strategically designed with a layer of waterproof membrane, the cover protects the memory foam from sweat or urine and can be removed for machine washing. The butt cushion also features vent holes that allow for ample airflow and never trapped body heat. Ergonomic Design. The unique U-cutout design floats your tailbone and hence alleviates pressure and minimizes coccyx pain. The slope and contoured surface shapes your lower body while providing support for your thigh with optimal comfort. Secure and Safe. To improve the safety of users in the wheelchair for daily activities, we designed a non-slip bottom and add a detachable cushion strap to fasten the wheelchair cushion in the wheelchair or other chairs (Remove the strap if of no need) Built for Daily Seat. AUVON memory foam cushion (18" x 16" x 3") fits most wheelchairs, and it can turn seats of scooters, office chairs, car seats, and dining chairs into comfortable seats.