PRO APF AGS LED Airfield Guidance Signs are used on airport taxiways to mark taxi routes and intersections, depending upon the governing standard, and to indicate remaining runway distance in thousands of feet. Eaton Crouse-Hinds offers FAA, ICAO and TP-312 approved LED signs for runways and taxiways. Colours may be black on yellow, yellow on black or white on red, depending on the application as defined by the governing standard.