The 3D armrests have been added with a forward and backward adjustment function. Users can adjust the height and rotation angle of the armrests. They can adjust the forward and backward position of the armrests according to personal needs, further optimizing arm support and reducing the pressure caused by long-term sitting. The forward and backward adjustment function of the armrests can meet the needs of different sitting postures. The 5508-3D armrests are characterized by providing more adjustment functions, which are suitable for users who have high requirements for sitting comfort.