Handy for use with the Pecolectrics SmartSwitch these LEDs (Light Emitting Diodes) can be used to give a visual indication of the route set on a turnout. They are either connected directly to the SmartSwitch Control board, or to the Control Board via a SmartFrog. By running wires from the SmartSwitch or SmartFrog to the the layout control position, the LEDs can be positioned on a track plan dislay panel (sometimes refered to as a "mimic panel") with the use of panel clips, which are included in the pack. Each pack contains 10 each of red and green LEDs, plus 20 panel clips.