Feature: DSP technology, more advanced and accurate. High-power output, loud and clear sound Wide-beam, high sensitivity, souffle filter Low ultrasonic acoustic output power, fully assured to monitor FHR. LCD large-screen display, blue backlight, display the real-time and average FHR. Optional rechargeable battery or AA batteries. Charge instruction, full battery indicator, lack of electricity indicator. Optional 2 or 3 MHz probe, portable for easy transport Automatically power-off, adjustable time of turning off, no background noise if no monitoring. Technical Parameters: Working Frequency: 2.0MHz Ultrasound Intensity: