Two audio frequencies available. Volume adjustment possible. Operating voltage: 9,5 - 28 V ac / 9,5 - 35 V dc. Current consumption: 40 mA ac / 20 mA dc. Sound intensity / frequency: 70 dB / 250 Hz or 70 dB / 750 Hz (intensity measured at 30 cm distance). Full sound intensity when operating voltage at least 15V ac or 18V dc.