OK, got a reply from Simonthewizard and he claims it is for freq. conversion but when I flip it, I see no change. Maybe I have to shut rig off, flip switch then turn back on. Have not tried yet. Or maybe the was a jumper or solder bridge removed also beforehand that made the switch operational? I found another Superstar/Dirland on eBay from France that has same switch inside but I am not ready for another headache just yet! LOL