These small white trim clips are used to attach the interior trim panel which hides the mountings for the door mirror. The trim is normally triangular and mounted at the front of the door window frame. There are normally 3 or 4 of these fasteners used on each cover depending on the model. If the door mirror is ever replaced, the trim will need to be removed and this will nearly always result in some of the clips needing to be replaced.
The clips are identical to GM part number 90560163 and are used on many different models across the Vauxhall and Opel range. They are not used on all models so check the photo and dimensions before you order.
Please check the details carefully before you order. Every vehicle has many different clips and fasteners. Even if the ebay compatibility check says these are used on your vehicle, that does not mean that they are the only clip and will be the ones that you need. It is important to check the photo, part number and dimensions before you order.