Modular bells and ringers are ideal for factories, farms, offices or any location where an audible signaling device is needed. Contains a modular jack that accepts line cords for plug-in installation and is available in single-line only. - 45-130 VAC Ringing Voltage (Phone line driven) - Loud ring up to 85+ dB - Mechanical ringer - Modular hook-up - Heavyduty - Two 4" bells - Ringer equivalency 1.0 Please note that if you have 5 or more phones connected to this phone line, the bell may not receive enough current to work.