Some 4 to 20 milliAmps displays come with annunciators that can be illuminated, “°F” and “°C”, “%” and “PSI”. All of these units come with customer selectable decimal points for display purposes. For applications that have low light, many of the meters come with optional backlighting. A separate 24 Volt DC power supply can be used to power the backlighting or it can be powered off the loop, as long as 24 VDC is available. If a separate power supply is used, the ground should be tied to the current loop ground.