Ultrasonic Pocket Doppler * Easy- to- use * Compact design * Interchangeable waterproof probe (sold separately) * Built-in audio recorder * Large backlight LCD display * Accurate FHR detection with high-fidelity sound effect * Support waterproof probes for both obstetrical and vascular usage * Auto Average and Manual working modes * Various power supply solutions * Automatic power-off to save power * 9V alkaline battery