When doing replacement or upgrading on 2009 – 2018 Mercedes-Benz G550 capsule halogen headlamps HID with, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

High Beam and Low Beam Headlight 2009 – 2010 9003
Front Fog Light 2009 – 2010 H8/H11/H16
Back Up Light 2009 – 2010 1156
Brake 2009 – 2010 1156
Dome Light 2009 – 2010 578
Front Side Marker 2009 – 2010 T4W
Front Turn Signal 2009 – 2010 1156
License Plate 2009 – 2010 12844
Parking Light 2009 – 2010 194
Rear Side Marker 2010 12929
2009 T4W
Rear Turn Signal 2009 – 2010 PY21W
Tail Light 2009 – 2010 12821
Luggage Compartment 2009 – 2010 6411
Courtesy 2009 – 2010 12961
Map Light 2009 – 2010 12961
High Beam and Low Beam Headlight 2009 – 2010 D1S
Front Fog Light 2009 – 2010 H8/H11/H16
Back Up Light 2009 – 2010 1156
Brake 2009 – 2010 1156
Dome Light 2009 – 2010 578
Front Side Marker 2009 – 2010 T4W
Front Turn Signal 2009 – 2010 1156
License Plate 2009 – 2010 12844
Parking Light 2009 – 2010 194
Rear Side Marker 2009 – 2010 12929
Rear Turn Signal 2009 – 2010 PY21W
Tail Light 2009 – 2010 12821
Luggage Compartment 2009 – 2010 6411
Courtesy 2009 – 2010 12961
Map Light 2009 – 2010 12961
High Beam and Low Beam Headlight 2011 – 2018 D1S
Front Fog Light 2011 – 2018 H8/H11/H16
Back Up Light 2011 – 2018 1156
Brake 2011 – 2013, 2015 – 2018 1157
2014 P21/5W
Dome Light 2011 – 2018 578
Front Side Marker 2011 – 2018 T4W
Front Turn Signal 2011 – 2018 PY21W
License Plate 2011 – 2018 12844
Parking Light 2011 – 2018 194
Rear Side Marker 2011 – 2018 12821
Rear Turn Signal 2011 – 2018 PY21W
Tail Light 2011 – 2018 1157
Luggage Compartment 2011 – 2018 6411
Glove Box 2011 – 2018 12818
Interior Door 2011 – 2018 194
Map Light 2011 – 2018 12961
Stepwell 2011 – 2018 12961