This diode bridge is only necessary to install when using an LED dashboard light for directional indicators. i.e. any of the GT or SS 5 light dashes.
Normally an LED will only work when positive current is connected to it's positive terminal, which causes a problem on the indicators as depending on which direction you are turning, positive current is swapped between the LED terminals. This diode bridge will enable positive current to always be on the positive terminal of the LED no matter which indicator is selected.
All of our LEDs use RED for (+) and black for (-), and this diode is sold compelete with an easy mounting bracket as shown in the 2nd photo.