When doing replacement or upgrading on 2007 – 2009 Mercedes-Benz R320 with capsule halogen headlamps HID, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

Low Beam Headlight 2007 – 2009 H7
High Beam Headlight 2007 – 2009 H7
Back Up Light 2007 – 2009 1156
Brake 2007 – 2009 1156
Daytime Running Light 2007 – 2009 PSX26W
Dome Light 2007 – 2009 194
Front Side Marker 2007 – 2009 12396NA
Front Turn Signal 2007 – 2009 3457NA
License Plate 2007 – 2009 12844
Parking Light 2007 – 2009 12961
Rear Turn Signal 2007 – 2009 PY21W
Tail Light 2007 – 2009 1156
Luggage Compartment 2007 – 2009 12961
Courtesy 2007 – 2009 6418
Map Light 2007 – 2009 12961
Low Beam Headlight 2007 – 2009 D2S
High Beam Headlight 2007 – 2009 H7
Back Up Light 2007 – 2009 1156
Brake 2007 – 2009 1156
Daytime Running Light 2007 – 2009 PSX26W
Dome Light 2007 – 2009 194
Front Side Marker 2007 – 2009 12396NA
Front Turn Signal 2007 – 2009 3457NA
License Plate 2007 – 2009 12844
Parking Light 2007 – 2009 12961
Rear Turn Signal 2007 – 2009 PY21W
Tail Light 2007 – 2009 1156
Luggage Compartment 2007 – 2009 12961
Courtesy 2007 – 2009 6418
Map Light 2007 – 2009 12961