Rail Extension is a direct fit for the following:

2021-2023 Buick Envision

2017-2019 Buick LaCrosse
2018-2020 Buick Regal Sportback
2018-2020 Buick Regal TourX
2019-2023 Cadillac XT4
2016-2023 Chevrolet Malibu

Genuine GM Part Number: 84240928