【Function】 BF-600 Portable Doppler can detect FHR and has a jack for telephone to connect Tele-monitor centre. 【Technology】 Power: 15V rechargeable batteries Ultrasonic frequency: 2MHz or 5MHz Ultrasonic intensity: ≤10mW/cm2 Work time: >8 H 【Unit】 net weight: 1.0kg gross weight: 1.8kg size: 230mm * 190mm * 135mm