ERGONOMIC DESIGN: Ergonomically engineered Synchro Tilt mechanism allowing users to tilt even while resting their feet on the floor. Adjustable Armrests and Seat Height and Cushioned lumber support. Lever under the seat allows you to lock this chair at 90 degrees and unlock it to rock back upto 105 degrees. Note: You can only lock this chair at 90 degrees and not at 105 degrees..BIFMA-certified GAS LIFT and P.U Cushion Seat with Hot pressed Plywood- The one-touch seat adjustment accommodates different workstation heights. P.U Cushion Seat offers the good under thigh support. Assembly Required: The product needs Complete Assembly. Screwdriver , Spanner & allen key required to assemble this chair..GLASS FILLED NYLON MESH BACK: Mesh back allows air to circulate giving your back relief while sitting for long hours of work. On the other hand glass with nylon gives this chair more strength and durability..CUSHIONED LUMBAR SUPPORT - The chair has cushioned lumbar support for exclusive comfort. It fits the shape of your spine; and provides support without putting pressure on any muscle groups..ADJUSTABLE ARMS: This JD9 Chair comes with adjustable arms which helps you rest your hand comfortably. Adjustable Arms helps you find the most comfortable seating position.