[Ergonomic lumbar chair] When you are spending more than 6 hrs sitting in the same position, a good chair is very important. With padded pillow and Reinforced framework mesh back support to fit your body curve to provide an extra comfortable experience. [Breathable mesh chair] The padded seat with a cover made of breathable mesh fabric uses Nanoscale materials that can resist transformation with high Density shaping Foam and abrasion to keep you comfortable during long, intense sessions. [Padded headrest chair] This computer chair features a slideable headrest that is made of breathable mesh, fitting the necks curve perfectly, making it great for relaxing during your busy working days. [Functional mechanism] Pneumatic controls make it easier to raise or lower the seat. The rocking mode can relax you from heavy work, pull out the handle to start rocking and pull it in to stop. The max weight supports up to 300 pounds. [Easy to assemble] Back Length: 20.1” X 26.8”(L X W), Size of Seat:16.6” X 19.7”(L X W), Seat adjustable height:17.3”-21.1”. No additional tools needed. For your convenience, all screws have extra backups.