suitable for use in cities, schools, hospitals and residential compounds Technical Parameters:Single-line receivers: Voltage: AC 110V-220VPower: 10W (MAX )Dimension: W270×D185×H50Weight: <2KGSupport receiving format (communication protocol): CONTACT ID,DTMF 4+2EXPRESS, 3/1,4/1 and 4/2 pulse(10-40pps),caller idCaller ID display format: FSKMaximum AUX police call current: 1A 30V