A monitor arm is almost necessary for a truly ergonomic workstation, especially if it is a standing desk. Since the height between your eyes and the desk can vary and change, especially between sitting and standing, you need a monitor that will rise and lower to the ideal height.
ergonomic monitor arms
What’s the Difference between Gas Piston and Metal Spring Counterbalance Mechanisms in Monitor Arms?
The most significant internal difference between different models is whether they are built using air cylinders or compression springs.