Tilt provides the option to recline backward and adjust a limit defined by control plate and chairs mechanism. The adjustment is controlled by turning a round knob found under the seat to the front/side of the chair. Paddles or levers are to maintain tilt lock, The single rod or lever which can be pushed or pulled out to unlock or lock the tilt. Once the tilt is positioned, it can be unlocked by reclining back a few more degrees to relieve the pressure from the pin or lock bar. Tilt lock remains entirely applied to the tilt if the chair is in the upright position.
One of the most important factor in choosing ergonomic chair is adjustable lumbar support. These chairs are extremely helpful for people who spend the majority of their work day at a desk. People who perform most of their tasks on a computer can especially benefit from chairs that provide proper support for their backs. The lumbar support should fit right in the natural curve of your spine, typically at the small of your back directly above your belt line. This adjustment is often built into the chair so you can adjust both the height of the chair back and the lumbar support at the same time. In some chairs, it's an independent adjustment.
3. Seat Pan Depth Adjustment
A seat pan with a sliding mechanism is a beneficial feature. This allows small and tall users to adjust the distance of the seat pan from the backrest. A person of smaller stature who sits on a long seat pan will experience pressure behind the knees, or will not benefit from the chair’s back support if he sits on the edge of the chair. A person of larger stature who sits on a short seat-pan length will have inadequate support of the thighs causing higher contact pressure
4. Synchro Tilt Adjustment
The synchronous mechanism (synchro tilt) combines a movement of the backrest and a corresponding smaller movement of the seat. The movement of the backrest is thereby larger than the movement of the seat. This allows the user to recline while keeping their seat relatively level to the floor instead of the traditional “rocking chair” type recline.
5. Armrest Adjustment
Armrest height is one of the most common ergonomic chair adjustments. The armrest adjustment can help with upper back. This is usually controlled by a push of a button or a simple knob, allowing to tilt the armrests inwards or outwards to varying degrees until it is adjusted to a comfortable position. The chairs’ armrest are adjustable in 1D, 2D, 3D and 4D which allows sitting close and working with arms relaxed.
6. Headrest Adjustment
Headrest adjustments provide support and comfort to the head and neck while in a reclined position, often keeping the head at a near-constant eye level with your computer monitor. The headrests are usually adjustable in height and angle to help the head remain centered on the neck and not lean forward.
7. Backrest Adjustment
Back adjustment ergonomics focus on positioning the spine, pelvis, and supporting muscles to prevent strain and promote a comfortable, healthy posture. This feature can be used by adjusting the button or knob on the side near the backrest and pull the back upward and downwards depending on the height of the user.
8. Height Adjustment
To use this feature, the user must pull the knob beneath the seat, which can be adjusted upward or downward based on personal choice. Sit back in the chair with your feet flat on the floor to get the desired foot position. Your thighs should be parallel to the floor, and your knees should be at a 90-degree angle or slightly wider. Your hip-knee alignment should be either level with your knees or a little higher. Once your knees and feet are in alignment, raise the chair so that your arms may comfortably rest at a 90-degree angle on the desk.
You may also refer to this link Ergonomic Chair Guide for more information.