SP-401 Solar RTIL Light (Runway Threshold Identification Light) is ICAO compliant solar-powered elevated airfield light designed for permanent usage at Non-Precision Runways located in regions without access to electricity and high photovoltaic potential.
ICAO, Annex 14th, Volume I, 7th Edition dated July 2016, clause 5.3.8.3 & clause 5.3.8.4, Appendix 1, Figure A1-1b