There are two adjusting rods, one is to adjust up and down, and the other is to adjust the backrest angle. You just have to try. Just pull up the lever for adjusting the backrest to straighten the backrest.
You are not the only chair in the world, and the adjustment method may be different. If you can't find the manual, then find out the brand model of the chair and find the brand official website online, so as to find the customer service phone number and call for consultation.
Generally, ergonomic chairs have headrest, because it is convenient for us to take a nap. Companies usually have time for employees to rest at noon to ensure their work energy in the afternoon.
If there is no headrest, you can only sleep on your stomach, but sleeping on your stomach will not only affect the respiratory system, but also affect the contour of your face.
Cushions are generally sponge cushions, but in recent years, the cushion material has been developed into mesh cloth, because sponges can be very boring to sit on, especially in summer. If the cushion is mesh, the air permeability will be much better. You can add a cushion according to your personal needs in winter.
Because a person's back can't be straight, the correct sitting posture should be curved, and the backrest is S-shaped, which can give a support to the waist, so it won't be very tired after sitting for a long time.
Ergonomic chairs have armrests, but some armrests can be lifted or adjusted in other ways, while others cannot. See if it feels comfortable when you put your hand on the handrail.
The quality of pneumatic rods should be very important, and there must be safety certification. Because the explosion of office chairs has happened before, mostly because the quality of air pressure rods is not up to standard, which will cause harm to users.
Although it may not explode without safety certification, I personally attach great importance to safety.