Bf-510 pocket fetal doppler
For this model there is no lcd display to show fhr.
It comes up with a headphone to hear fhr very clearly.
It can work with dry battery or rechargeable battery.
Please find the following specifications:
Ultrasonic frequency: 2.0mhz
Power: 9.0v dry battery or 9.0v recharge battery
Ultrasonic intensity: _10mw/cm2
Work time: 4 hours
