Feature: Easy to use Accurate FHR detection and LCD display with the backlight on or off Built-in speaker for listening to the heartbeat without headphones Headphone jack for listening to the heartbeat or attaching to the computer with the included accessory for recording the heartbeat 2 AA size batteries Low battery consumption and Auto OFF feature Battery icon indicates how much battery life is left Fetal Doppler Displays Three Modes: Mode 1: This mode displays fetal heart icon when fetal heart beat is detected and also displays the real-time heart rate numerically. Mode 2: This mode displays the fetal heart icon when the fetal heart beat is detected and averages the fetal heart rate for a more stable reading. Mode 3: This mode can calculate an average fetal heart rate over a specific period of time by manually pushing a button to start and stop the time