These fasteners are common on many Peugeot and Citroen cars and are used to attach the panels that run on the underside of the car beneath the engine bay. The parts are often lost or damaged during routine servicing or usage. If missing or loose then there is a risk of the undertray detaching during driving.
These are not used on all cars and will not be the only type of clip used on any car so please check before buying.
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.