When doing replacement or upgrading on 2010 – 2018 GMC Terrain 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 Headlight2010 – 2017 H11
High Beam Headlight2010 – 2017 9005
Front Fog Light2010 – 2015 H8/H11/H16
Back Up Light2010 – 2017 921
Brake2010 – 2017 3057
Dome Light2010 – 2017 12961
Front Side Marker2010 – 2017 194
Front Turn Signal2010 – 2017 7444NA
License Plate2010 – 2017 194
Parking Light2010 – 2017 7443NA
Rear Turn Signal2010 – 2017 3057
Luggage Compartment2016 – 2017 194
Inner Tail Light2010 – 2017 194
Map Light2010 – 2017 12961
Outer Tail Light2010 – 2017 3057
Low Beam Headlight2018 H11
High Beam Headlight2018 9005
High Beam and Low Beam Headlight2018 D5S
Front Fog Light2018 H8/H11/H16
Back Up Light2018 921
Brake2018 3057
Dome Light2018 194
Front Side Marker2018 194
Front Turn Signal2018 7443NA
License Plate2018 12961
Parking Light2018 7444NA
Rear Turn Signal2018 7440
Luggage Compartment2018 194
Inner Tail Light2018 194
Map Light2018 12961
Outer Tail Light2018 3057