1.Accurate and reliable FHR detection with clear sound 2. 3.0MHz probe with 2.0MHz ... be used in any illumination conditions.2. Accurate and reliable FHR detection with clear sound 3. High sensitivity probe with 2.0MHz ... batteryContinuous working hour>4 hoursMeasuring ModeMean, Average, Continuous, BacklightDisplay3 digital FHR,Battery low,Voice,Ultrasound frequency,Mode typeButtonON/OFF, Voice Control ...