Locate Back Contact Before Moving The Backrest
Ask the user to sit as they normally would for desk work and describe where the backrest makes contact. Observe the relationship between the seat and the backrest before changing anything. This creates a reference for assessing the adjustment, rather than moving the backrest through its available positions without a clear reason for selecting one.
Raise or lower the backrest according to the chair's instructions and compare the resulting contact. Do not assume that the highest position offers the most support or that the lowest is appropriate for every shorter user. The relevant outcome is how the particular backrest shape relates to the individual within a workable seated position at the desk.
Examine Range, Access And Operating Method
Confirm how far the backrest can move and how that movement is controlled. Adjustable back height does not specify a lever, ratchet or any other mechanism. Request a demonstration for the individual chair, including how a position is selected and retained. Assess the actual process rather than relying on familiarity with another chair's controls.
Include the intended users in that demonstration. Check whether they can identify the adjustment, understand the sequence and recognise when it has reached the desired position. Record any setup assistance required. If chairs will be used independently across a large office, the clarity of the instructions deserves attention alongside the available movement and the fit achieved during a guided trial.

