Only 1 LED will be illuminated at a time. Connections: The "+" terminal is for a positive volt connection. The "-" terminal is for the negative or ground connection. The "C" terminal is for when being installed through a key switch or direct connection. Please review the installation instructions for the correct wiring diagrams. Dimensions: Overall: Width 2 1/16" ; Height 1 1/4" Hole cutout - 1 3/8" wide by 7/8" high Depth Behind front meter flange to end of mounting screws - 1 1/8 inches