What do the two levers on the Dauphin Viper chair do? One is to adjust the height of the seat and the other?

Answer 1

Here is the description from the manufacture, about your chair\
Dauphin Viper Mesh Back Chair with Headrest features a synchronized seat and backrest adjustment with 4 position lock out feature and independent weight tension control.

Other features include pneumatic seat height adjustment and height adjustable arms with rotating extendable arm caps.

The incredibly strong fiberglass reinforced polyamide base has 2" dual wheel free-rolling carpet casters.