Push Fasteners or “Xmas Tree” Retainers: Used for retaining door panels, interior trim, hood insulation, weatherstrip, splash guards, headliners and various fascia. Although OEM interior retainers come in a large variety of colors, the aftermarket parts are usually black or natural nylon. The body shop paints them to match the application as needed. There are several different variations of design. The multi-head type twists into a slit on the trim panel and then the stem gets popped into a hole in the sheet metal. These parts are usually destroyed when removed.