Description: fetal Doppler. Model number: JSL-T502. Range of fetal heart rate measurement: 65 bpm–210 bpm. Ultrasonic operating frequency: 3.0 MHz (optional 2.5 MHz and 2.0 MHz). Resolution of fetal heart rate detection: 1 bpm. Fetal heart rate measurement error: not more than ± 2 bpm. Ultrasonic radiation power: <20 mW. 6. spatial-peak pulse pressure: <0.1 MPa. Screen: 39 mm x 31 mm LCD display. Dimensions: 128 mm x 96 mm x 30 mm. Weight: approximately 161 g (without battery). Power supply: DC3V (2×AA) battery. Storage conditions: temperature -20°C–55°C; humidity ≤93% RH; atmospheric pressure: 86kPa–106kPa. Operating conditions: temperature 5°C-40°C; humidity: 15% RH-85% RH; atmospheric pressure: 86kPa–106kPa.