Features SIHOO ergonomic chair with adjustable headrest can make neck tilt easily and comfortably, adjustable lumbar support bracket for free adjustment of height depth, 3D adjustable armrest for different office applications, 90 -126 arbitrary backrest adjustment for multiple work positions, any switch 3.15 in lift, 360 Freedom to rotate freely 3D handrail. Ergonomic design SIHOO ergonomic office chair is recommended by Ergonomics Application Association. SIHOO's ergonomic design is based on the human body dynamic digital model. The ridge backrest and the human spine are exactly the same. The close fitting helps release the spinal pressure. The flow waterfall arc seating design Thigh support is comfortable, SIHOO will make you more comfortable.