The Harper fits the back dynamically in any sitting posture and every adjustment of the angle always gives the most suitable support to the spine. It's 3D adjustable armrests provide suitable heights and angles support for different sitting postures, relieving upper back and shoulder pressure. The comfortable waist support cushion is made with high elastic foam that can be adjusted to better support the lumbar spine. Installation is quick and easy; only two screws are needed in the whole process of assembly.3-point Synchro Mechanism5-Levels Tilt Angle AdjustmentAdjustable seat depth range of 2"Adjustable Lumbar Support3D Adjustable Armrest17"-20" Seat Height19" Seat Width18" Seat Depth