This tray accessory is used to switch off the power to the monitor.
No need to touch the monitor switch.
Click the mouse or press a (configurable) function key to turn the monitor off whenever you want and don’t need it to be on.
With MonitOff you save electricity because less energy is wasted when you are not at the keyboard. The computer is not turned off so it can continue working with other stuff (playing music, downloading files, etc) just the screen is off. It is actually unpowered not just black.
Using MonitOff will reduce considerably your electrical bill. The amount of hot air surrounding the computer (provided they are at the same room). This will improve other hardware efficiency, cpu cooling and ventilation.