This is a table module plugged into the main panel circuit board. The white rectangle is the LED  which produces the Red, Green and Amber light. Just below the LED is the Hall effect switch which changes the lights. This device is 100% solid state, no moving parts to break. Note when changing a table module do not scratch or pry off of the main circuit board.
LED  light emitting diode - a semiconductor diode that emits light when voltage is applied. This device has a life expectancy at the voltage applied by our system that exceeds 50 years. There will be no need to change a LED due to a burn-out in normal applications.