Feature: 1. High Fidelity Speaker: Built into 38 quality sound effects with low power. There is always one for you. Voice clear and there are variety of sound effects. 2. 4 Gears Volume Adjustment: Farewell embarrassed of inaudibilit. With intelligent volume adjustment, don't worry about inaudible. (Note: It is recommended to adjust the volume to level 1‑2 for daily use.) 3. One Button Mute: To avoid disturbing the elderly and children. Can choose mute mode, only flashing lights without ringing the bell to avoid waking the sleeping baby or the elderly. 4. 433MHzH Frequency Modulation Signal Scheme: The transmission of strong signal penetration is more than 200 meters, to meet all kinds of life needs. 5. 120° Sensing Angle: Adopt imported infrared probe, universal rotation 120° sensing area, sensing distance 3‑7 meters, sensitive and free. 6. Protective: During the day and night, when there is no one at home, someone opens the door and the doorbell rings to trigger the burglar alarm, protecting the safety of family and property. Specification: Item Type: Sensor Doorbell Product Material: ABS Weight: Approx. 170g / 6.00oz Transmission Distance: Approx.>200m/7874in (open space) Induction Angle: 120° Induction distance:Approx 3-7m/118.11-275.59in Radio: Frequency:433MHz Ringtone: 38 Induction Head Power Supply: 3 AAA batteries (not included) LED Color: Blue light. Package List: 1 x Acceptor1 x Sensor probe1 x Shield1 x Fixed Head1 x Holddown Groove 2 x Lag Spike2 x Expansion Pipe1 x Specification