Abstract: Provided is a plastic fastening mechanism including an intermediate main body having an axial, shouldered first through hole, two wings each having an axial, shouldered second through hole, and two flexible interconnections each formed between the wing and the main body; and elastomeric first and second elements each shaped to conform to the rear of either the first or second member. The main body is threadedly secured to a chair J-bar and the wings are threadedly secured to chair backrest. The main body of each of another two plastic fastening mechanisms is threadedly secured to the J-bar, and the wings thereof are threadedly secured to chair headrest. Moreover, there are provided two elastomeric mechanisms shaped to conform to the rears of the fastening mechanisms. The elastomeric mechanism includes an intermediate, hollow member, two side receptacles, and second interconnections each formed between the hollow member and either receptacle.