1Night Lighting Compass: The wires use to connect an external 12V power supply to illuminate red light when night use, you can choose not to connect it if you only use it in day time, that depends on your need. 2Magnetic Declination Adjustment: There are two holes, which can adjust the magnetic declination in the east?west direction and the north?south direction. This function is special for someone more precise needs. Actually it does not require additional adjustment when daily life. 3Usage Notice: The scale reading on the red indicator line indicates your forward direction. The direction of the marine compass is opposite to the direction of the ordinary compass, marine compass shows the direction you are going, not the direction of the geomagnetism. 4Horizontal Place: Please adjust the compass on a horizontal level, make the compass can be can be free to rotate. Please make it stay away from other magnetic objects that may disturb it's function. 5Easy Installation: Packaged with double?sided tape and screws, you just need to fix it on the boat dashboard with the double?sided tape, then it is ready to use. Universally appropriate for car, automobile, vehicle, marine boat, yacht, Rv, caravan, etc.