Features:Pocket Fetal Doppler mainly applies to detect the fetal heartbeat rate from the twelfth week; LCD can display FHR accurately;Built-in rechargeable battery can work continuously more than 5 hours;Only 220g, can be carried conveniently with a gallus;Alarm function when FHR is out of the normal range or battery power is in shortage;Built-in speaker and collocated with earphone jack;2.5MHz probe and easy to replace. Specifications: Executive Standard: EN61266: 1995Ultrasonic frequency: 2.5MHz±10%Ultrasonic intensity: ≤10mW/cm2Comprehensive Sensitivity: ≥90dBFHR range: 60-210bpm(±2bpm)FHR alarm range: ≤100bpm or  ≥160bpmIsptp: ≤0.1MPaBattery: 9.6VNi-MH rechargeable batteries Adapter input voltage: AC 110V±10% 60Hz / 220V±10% 50Hz Rechargeable battery input voltage（no load）: DC 12V±1VMaximum audio output intensity: ≤1WDoppler frequency: 100--3000HzStatic continuous working time: ≥5hWorking temperature: 10-40℃Humidity: ≤80%Atmospheric pressure: 86--106kPa