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 Headlight 2010 – 2017 H11
High Beam Headlight 2010 – 2017 9005
Front Fog Light 2010 – 2015 H8/H11/H16
Back Up Light 2010 – 2017 921
Brake 2010 – 2017 3057
Dome Light 2010 – 2017 12961
Front Side Marker 2010 – 2017 194
Front Turn Signal 2010 – 2017 7444NA
License Plate 2010 – 2017 194
Parking Light 2010 – 2017 7443NA
Rear Turn Signal 2010 – 2017 3057
Luggage Compartment 2016 – 2017 194
Inner Tail Light 2010 – 2017 194
Map Light 2010 – 2017 12961
Outer Tail Light 2010 – 2017 3057
Low Beam Headlight 2018 H11
High Beam Headlight 2018 9005
High Beam and Low Beam Headlight 2018 D5S
Front Fog Light 2018 H8/H11/H16
Back Up Light 2018 921
Brake 2018 3057
Dome Light 2018 194
Front Side Marker 2018 194
Front Turn Signal 2018 7443NA
License Plate 2018 12961
Parking Light 2018 7444NA
Rear Turn Signal 2018 7440
Luggage Compartment 2018 194
Inner Tail Light 2018 194
Map Light 2018 12961
Outer Tail Light 2018 3057