When doing replacement or upgrading on 2009 – 2018 Ford Flex with halogen capsule headlamps HID, 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 Headlight2009 – 2018 9008
Front Fog Light2009 – 2018 H8/H11/H16
Back Up Light2009 – 2018 921
Brake2009 – 2018 4057
Dome Light2009 – 2018 578
Front Side Marker2009 – 2018 194
Front Turn Signal2009 – 2018 3457NA
License Plate2009 – 2018 6418
Parking Light2009 – 2018 3357NA
Rear Side Marker2009 – 2018 194
Rear Turn Signal2009 – 2018 4157
Luggage Compartment2009 – 2018 578
Glove Box2009 – 2018 161
Inner Tail Light2009 – 2018 194
Map Light2009 – 2018 12961
Outer Tail Light2009 – 2018 4157
High Beam and Low Beam Headlight2009 – 2018 D3S
Front Fog Light2009 – 2018 H8/H11/H16
Back Up Light2009 – 2018 921
Dome Light2009 – 2018 578
Front Turn Signal2009 – 2018 3457NA
License Plate2009 – 2018 6418
Parking Light2009 – 2018 3457
Luggage Compartment2009 – 2018 578
Glove Box2009 – 2018 161
Map Light2009 – 2018 12961