A fixture for mounting on a support structure having an outer surface and an inner surface defining a thickness, with a bore therethrough, comprising: a tubular body, having a top section and a bottom externally threaded section; a retaining collar, having an upper portion, the bottom surface thereof larger than the bore, and a circular internally threaded lower portion smaller than the bore; a keeper body, having an internally threaded circular passageway, including a ring shaped upper part having an outside surface and an outside diameter slightly smaller than the diameter of the bore, and a lower part having a smaller diameter than said upper part, the retaining collar and keeper body sized for threading onto the tubular body; and pivotable, rotatable ears having an upper edge and a lower end providing a stop, mounted to the upper part of the keeper body.