There is a small hole drilled through each knob to let the existing light source shine through. But not very much. I've been toying with the idea of popping the knobs back off and re-drilling the holes slightly larger, and inserting colored acrylic rods. Should work like fiber optics that way.Anyway, I had a question about those knobs.. is there any LED in them, or at least something that allows the backlighting from the factory knobs to show through? Can't tell from the pics.