ERGONOMIC BACK: This swivel computer chair is thoughtfully designed with S-shaped back to fit in curvature of individuals back and lumbar. It gives full support to your lumbar and upper-back to make your long office hours and intensive study sessions easier in a better sitting position. ADJUSTABLE SEAT HEIGHT: Seat height of our ergonomic computer chair can be adjusted for 45-55cm/18-22. It has the flexibility to customize our customers preferred sitting position according to their needs. Simply pull the lever beneath the seat while sitting if you want to lower the seat.