The EVS is the fastest way to test various Fire Alarm Devices that would otherwise require removal of said device from the wall/backbox in order to access the wiring.

Once installed the testing time is reduced from minutes and even in some cases hours to mere seconds.

The dust and water caps are to protect the EVS from installation dust and water splash, from entering the front of the EVS. They can be left on after installation, if the environment the EVS is installed in, is prone the dust and or water splash.