These clips are used on a massive range of VW and Audi models to attach interior trim panels. This clip is 22.3mm long. They do another very similar looking clip which is 16mm long. To find this part, search ebay for "FCP-0404". The clip is commonly used for boot and tailgate linings.
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.