I didn't know that but it make sense. Seal beams have a diffusion panel which would throw light up whereas projector lens don'tHeatseeker said:Reflecting part of the beam upwards is part of the DOT spec, btw.
Aha!Heatseeker said:Those aren't slots.
They are reflective ridges molded into the body underneath the cover, and they serve to project a small amount of light upwards to light overhead signs.
Reflecting part of the beam upwards is part of the DOT spec, btw. Many projector beam headlamps use something similar. One example -- the MKIV Supra has ridges identical to those, which serve the same function.