Dual Projector Headlights(primary Light Source?)

[99Mustang1616]

I've been seeing the Raxiom dual projector headlights on mustangs, but are the halo rings you see the primary source of light at night? Or is there a light that comes on in the middle that lights up the road because the headlights I have now on my 99 gt have the rings, but they only come on from a switch next to my parking brake. They aren't the primary source on my headlights. Just for looks. What I am wondering is that is this what all projector headlights are like? Or are the rings the primary source for driving.