Many of these parts are supplied with the clips already fitted, and some are supplied bare, which is worth checking before ordering.
These panels are replaced after collision repair, after a leak has stained or warped them, or when a mounting tab has broken and the panel no longer sits flush. On wagons and hatchbacks the rear quarter trim also houses the speaker and the cargo tie-downs, so the part number changes with the audio option.
Fitment is decided by body style and trim level. A sedan quarter trim will not fit a wagon, and a panel for a vehicle with a sunroof has a different upper edge from one without. Confirm the body style from the VIN rather than from the model name, and match the colour from the trim code on the identification label.