Fetal heart rate performance features: 1. Switch between two measurement modes of digital curve at will. 2. OLED blue and yellow two-color display, clear reading 3. One-piece design, streamlined appearance and strong sense of experience 4. Handy and compact, easy to carry and use 5. Two AA batteries (not included) 6.Parameters of fetal doppler:Probe frequency:3.0 MHz plusmn10%Error range
