When doing replacement or upgrading on 2005 – 2018 Buick LaCrosse 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.

Low Beam Headlight 2005 – 2009 H11
High Beam Headlight 2005 – 2009 H9
High Beam and Low Beam Headlight 2017 – 2018 D3S
Front Fog Light 2005 – 2009, 2017 – 2018 H8/H11/H16
Back Up Light 2005 – 2009, 2017 – 2018 921
Brake 2005 – 2009 3057
2017 – 2018 7440
Daytime Running Light 2005 – 2009 H8/H11/H16
Dome Light 2005 – 2009 194
Front Side Marker 2005 – 2009 194
Front Turn Signal 2005 – 2009 4157
License Plate 2005 – 2009, 2017 – 2018 194
Parking Light 2005 – 2009 4157
Rear Side Marker 2005 – 2009 194
Rear Turn Signal 2005 – 2009 3057
2017 – 2018 7440
Courtesy 2005 – 2009 194
Glove Box 2005 – 2009 194
Inner Tail Light 2005 – 2009 194
Map Light 2005 – 2009 168
Outer Tail Light 2005 – 2009 3057
Trunk 2005 – 2009 912
Low Beam Headlight 2010 – 2013 H11
High Beam Headlight 2010 – 2013 H9
High Beam and Low Beam Headlight 2014 – 2016 9012
Front Fog Light 2014 – 2016 H8
2010 – 2013 H8/H11/H16
Back Up Light 2010 – 2016 921
Daytime Running Light 2014 – 2016 7443
2010 – 2013 H11
Dome Light 2010 – 2013 194
Front Side Marker 2010 – 2013 3757NA
2014 – 2016 7443
Front Turn Signal 2010 – 2013 3757NA
2014 – 2016 7444NA
License Plate 2010 – 2016 194
Parking Light 2010 – 2013 3757NA
2014 – 2016 7443NA
Rear Turn Signal 2010 – 2013 3757NA
2014 – 2016 7440NA
Glove Box 2010 – 2013 194
Interior Door 2010 – 2016 194
Map Light 2014 – 2016 12961
High Beam and Low Beam Headlight 2010 – 2013 D1S
2014 – 2016 D3S
Front Fog Light 2014 – 2016 H8
2010 – 2013 H8/H11/H16
Back Up Light 2010 – 2016 921
Daytime Running Light 2010 – 2013 3157
Dome Light 2010 – 2013 194
Front Side Marker 2010 – 2013 3757NA
Front Turn Signal 2010 – 2013 3757NA
2014 – 2016 7444NA
License Plate 2010 – 2016 12961
Parking Light 2010 – 2013 3757NA
2014 – 2016 7443NA
Rear Turn Signal 2010 – 2013 3757NA
2014 – 2016 7440NA
Glove Box 2010 – 2013 194
Interior Door 2010 – 2016 194
Map Light 2014 – 2016 12961