This ergonomic office chair takes into account the physiological structure of the human body, designed with a double-back structure, providing lumbar good support and reducing fatigue and discomfort.Pneumatic controls make it easier to raise or lower the seat, which allows you to pick the appropriate level for long-term comfort. Features Flip-up Arms & Adjustable Headrest：The Mesh computer chair can be flipped up 90° to fit different needs and small place, saving space. Breathable & Comfort: The mesh office chair is designed with high-quality premium mesh. The breathable mesh allows increased air circulation for refreshing experience. Durable & Stability: The large seat cushion with widened design is softer and more elastic, and it is not easy to sink and deform after long-term use. The maximum weight capacity is 300 lbs. Lockable Tilt Function: The backrest of the ergonomic office chair can be reclined within a range of 90°-135°,meeting your needs for different scenes and sitting postures. In addition,the angle and height adjustable headrest provides the most comfortable position for your neck. Easy Assembly: We have provided instructions and installation tools for each seat. So you can refer to the steps in the instructions and the installation can be completed in 15 minutes.