TECHNICAL SPECIFICATIONFETAL DOPPLER �Model: NEOSTAR I�Display: LCD with FHR Numerical Value, Bar Graph, Battery level, Volume level and mode indication.�2.5 MHz Ultrasonic Transducer Probe.�Battery: 3.6 V, 3000 mAh Ni-MH�Charging Time: 4 hrs.�Working Hours: 8 hrs.�Rechargeable like mobile.