Center-Tilt Tension: There is a tilt tension knob beneath the seat to adjust the recline angle and amplitude of the backrest. Customers can simply tighten or release the center-tilt tension by turning the control knob left while rocking back and forth.360° Swivel Chair: Five mute rolling castors serve a smooth and effortless movement, these nylon wheels can move from any direction without causing scratches on the floor. Nylon wheels are sturdy and durable, capable of long-term usage.Quick and Simple Assembly: All the necessary parts, hardware and easy-to-follow instructions are included in the package for a simple 5-step setup within 15 minutesPacking List:Office Chair × 1Instruction × 1.