Royaloak Joy Computer chair has a firm foam cushion upholstered with nylon knitted fabric, which makes long hours at your desk comfortable. The flexible high-grade nylon mesh back is designed for air-circulation and support when you lean back the curvey shape supports the lumbar area. Adjust the height using the gas lift to find that comfortable position and the nylon castors make it easy to move around your space. fixed armrest to rest your arms . thischair comes with single lever to adjust height and lock the back rest.