Computer chair chassis quality

Chassis: The part that holds up the seat, and the bottom is connected to the air rod. Many of the chair chassis with retail price below 160 yuan have no casing. After long time, it is easy to crack and shake. It is easy to have some iron plate thickness. The amount of caliper is only 1.7mm thick. It is usually 1.9mm thick. The spring of the chassis is not long enough or heat treated. Heat treated new spring with a liver color instead of iron.