1.Open structure 2.Dimension: D16*12mm 3.Frequency: 25kHz, 28kHz, 23KHz 4.Using method: Transmitter/Receiver 5.SPL:min.115dB/10V/30cm 6.Sensivity:min.-65dBv/ubar 7.Capacitance: 2200pF Housing material:Aluminum, Plastic