DOORBELL ORBIS_OB110330CH doorbells in residences, workplaces, and structures. The main entrance's ding-dong sound. - Two musical notes on a bell. An electromechanical doorbell that is long-lasting and has a large capacity. Ding-dong sound: resonance at 900 Hz, frequency at 700 Hz, and volume at 90 dB. Technical features 120 is the rated voltage.