This clip is 16mm long. They do another very similar looking clip which is 22mm long. The clip is commonly used for boot and tailgate linings.
10x Audi Boot Tailgate Lining Metal Trim Panel Clips- Metal Interior Trim Clips
QWORK® 10X CV Boot Clamp, Adjustable Axle Boot Clamp, Stainless Steel, 20-50mm / 50-120mm
10x Audi 5mm Plastic Rivets- Trim Clips for Bonnet Seal, Bumper, Spoiler & Dash
VW AUDI BOOT TAILGATE TRIM PANEL LINING UPHOLSTERY METAL SPRING CLIPS INTERIOR
10 x Audi Boot Screw Exterior Lining Fastener Retainer Metal Trim Panel Clips
FIT AUDI BOOT TAILGATE INTERIOR LINING METAL TRIM PANEL CLIPS
