Federal Signal's Vibratone® bells models 504WB 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 these bells are offered in 120 VAC. Vibratone® gongs are tempered to give them superior output and long-lasting durability. Models 504WB both contain internal terminal blocks to simplify installation. This method also allows for an uninterrupted, single run of wiring.