Vibratone® Bell Assembly Models 504WB and 506WB are completely assembled and include the gong, vibrating AC mechanism, and the gasketed back box. These assemblies feature heavy-duty, industrial grade housings and powder-coat paint treatments for added durability and performance.Vibratone gongs are tempered to produce superior output and long-lasting durability.Both models contain internal terminal blocks which simplifies installation. This method also allows for an uninterrupted, single run of wiring.