Chx-2c++ portable fetal doppler ( two led display ) It's used for detecting the fetal heart rate(fhr) at hospital, clinic, family. Easy to use Two led display fhr of real-time and average Built-in speaker Sound alarm function when fhr is out of the normal range Built-in rechargeable battery Specification: Ultrasonic frequency: 2.5 mhz Dimensionú¦185(l)* 190(w)* 130(h)mm Weight : 1.3kg Continuous work time: 8 hours Specification: Ultrasonic frequency: 2.5 mhz Dimensionú¦185(l)* 190(w)* 130(h)mm Weight : 1.3kg Continuous work time: 8 hours