The Kit consists of 10 Red LED's, 10 Green LED's, 10 Resistors 1K, and 20 Panel mounting Bezels.
The Bezel requires a 6.35mm hole in the control panel, and the LED is pushed into the bezel from the underside thereby locking the LED and Bezel in place on the panel.
Can be used to indicate signals, points, level crossings, train positions, and many more.