the last time I looked their masthead didn't have a photodiode, so it has to be manually switched on & off at dusk & dawn ... surprising for such an expensive piece of equipment. I have an OGM Tri w/strobe on my mast and they have been very good to me ... replaced a part once on the switch that I broke while installing ... then sent me a complete new light with an RF installed as it was causing interference with my VHF, both times free of charge. Mine is now 3-4 years old and it works well. It has the photodiode which I think is very nice to have. It's amazing how many times the old light was left on during the day, consuming 1Ah all day long, what a waste. cheers, John