I bought my Honda used, I was changing the instrument bulb and had the headlight apart, and found it had a modulator in there that was incorrectly installed. I fixed it, but I don't always use it.

It has a light sensor mounted to the outside, if its daylight out, you flip the high beam switch on and it modulates, at night the sensor knows its dark out, and the switch only turns on the high beams.
I use it in daylight sometimes, if I see a douche bag car up ahead about to pull out or whatever and I don't think they are paying attention. I might flip it on for a bit as I get closer.