Feature: 1. Multifunction Volume Setting: Using high fidelity speakers, low power consumption, built in 38 high quality sound effects. The volume can be adjusted intelligently. Four gears are optional. You don't have to worry about being unable to hear or hear clearly under special circumstances. (Note: it is recommended to adjust the volume to 1‑2 for daily use.) 2. Mute Function: One click mute without interruption is the gospel of the elderly and children. The mute mode can be selected. Only the light flashes without ringing to avoid waking the sleeping baby or the elderly. 3. Strong Wireless Signal: It has strong penetration. 433mhz FM signal scheme has strong penetration. The signal transmission is greater than 200m, meeting various living needs. 4. 120° Sensing Angle: The smart doorbell adopts imported infrared probe, 360° universal rotation, 120° sensing area and sensing distance of 3‑7m. 5. Security Alarm: It closely guards the safety of people and money. When there is no one at home during the day and night, someone opens the door and the doorbell triggers the anti‑theft alarm to protect the safety of family and property. Specification: Item Type: Smart Wireless Sensing Doorbell Material: ABS Weight: Approx. 224g / 7.9oz Transmission Distance: > 200m (Open Ground) Sensing Angle: 120° Sensing Distance: 3-7m / 118.1-275.6in RF Frequency: 433MHz Ringtones: 38 One for Two: The alarm is installed indoors, and two sensors can be installed at the door or garage for monitoring Power Supply of Single Sensor Head: 3 AAA Batteries (Excluding) LED Color: Blue. Package List: 1 x Receiver1 x Sensor Head2 x Shield2 x Fixed Heads 2 x Fixed Slots 4 Screws 4 x Expansion Tubes1 x Manual