LOUD RINGTONES & LED INDICATORS: The wireless motion detector provides 38 different ringtones and 4-level volume control. You can use the music button to customize the doorbell alarm sound according to your personal preference at any time. You will never miss a visitor. MOTION SENSOR ALERT RANGE: The doorbell siren detects movement within a range of 3m to 7m and sends a signal to receivers up to 200m away, ideal for keeping you informed before guests or intruders arrive. . EASY TO INSTALL: Simply place 1 transmitters at the entrance of the driveway or near windows and place the receivers around your home. The sensor requires 3 AAA batteries to operate (not included), and the receiver is plugged into a standard outlet or powered by USB (not both, otherwise the batteries will heat up and cause a safety hazard). WIDE APPLICATION: Our infrared doorbell alarms are widely used in your home, office, store to alert you when someone enters your garage, sidewalk, door or business, which can