Yeah that is a special bulb bro...no wonder I was confused as only those two bulbs do that. Here is how: shielding on the bulb itself is used to form more of a "cutoff" in the reflector housing
Whatever bro, get a real HID setup...hahahaha...jk
P.S. Careful though bro with D2R bulbs as they contain mercury; the D4R replaced it to remove that.