Abstract: A one piece plastic fastener for supporting secondary members relative to a thin panel in a shouldered non-circular aperture. The fastener provides a wide distribution of stress loading by a large hook-like prong which is rotated into contact with the backside of the panel by telescoping it through the aperture until the head covers the aperture. A resilient arm extends from the prong into engagement with the edge of the non-circular aperture to prevent unintentional retrograde motion of the fastener. The fastener can be removed, if desired, by introduction of a thin member under the head to unseat the resilient arm.