U-shaped cushion, lightweight and comfortable. Thank you for viewing. I bought a new chair and no longer need this, so I'm selling it. It was comfortable; sitting properly on the seat really helped prevent my buttocks from hurting. It might be good for those who sit with good posture, or perhaps for wheelchairs, as it uses medical-grade gel. I think it's also good for everyday use on office chairs, kitchen chairs, and gaming chairs. Brand: EXGEL Features: Removable cover Color: Gray Size: W410 x D400 x H37 (mm) Material: EXGEL Shape: Semicircular The U-shape prevents pressure on the coccyx and sacrum. Unlike typical donut-shaped cushions, you can sit deeply, providing a stable sitting experience. The secret to comfort is the exquisite balance of EXGEL, which is soft but doesn't sink in too much, and urethane. The base urethane has different hardnesses in the front and back. The rear of the cushion uses firmer urethane to stabilize the pelvis, while the front uses softer urethane to reduce pressure on the back of the knees. It comes with a washable, quick-drying cover for home use. The bottom of the cushion body and cover have non-slip processing for a secure sitting experience. Unlike typical donut-shaped cushions, you won't feel pressure on the back of your buttocks, allowing you to sit deeply. Also, the flat seating surface with reduced thickness naturally encourages a stable posture. When sitting, the body unconsciously moves vertically and horizontally to relieve stress. EXGEL's pressure-relieving and flow-dispersing properties continuously adapt to those movements. It protects the body gently, like a human hand.