This user friendly multi probe has white backlight LCD so it easily displays FHR in the dark, including probe frequency, Doppler signal, battery capacity and alarm indicator. Output jack makes for easy connection to other instruments including headset. It provides sound enhancement and record functionality. Typically probe is used at 2 MHz but it can be changed to 3 Mhz, 5 Mhz or 8 Mhz with an error rate of ± 10%, and a ?10mW/cm2 intensity in ultrasonic power with a ?90dB sensitivity. The doppler’s frequency is 0-3KHz. Power consumption is ?1.5W, and you use either rechargeable batteries or a 1.5 V alkaline battery. Powers of after 3 minutes.