This is a door panel retainer. Useful for a variety of applications, it is OE for GM models (1984-present).  It matches GM OE Part Number 20429451. Although this retainer is OE for GM vehicles, it is universal and can be used on any vehicle or application requiring this type of retainer and meeting these specifications.
                                                                                    Material: Nylon
                                                                                    Fastener Type: Triple Head
                                                                                    Top Head Diameter: 23/32"
                                                                                    Bottom Head Diameter: 23/32"
                                                                                    Stem Diameter: 5/16"
                                                                                    Stem Length: 5/8"
                                                                                    Color: White
                                                                                    Matches OEM Part Number: GM: 20429451