1、4 Gear Volume Adjustment: Intelligently adjust the volume, 4 gears are optional, and there is no need 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 Key: One click mute and no disturb function, you can select the mute mode, only flash the light without ringing, so as to avoid waking up the sleeping baby or the elderly. 3、Strong Wireless Signal: 433mhz FM signal scheme with strong signal penetration. The signal transmission is greater than 200m, which can meet various living 4、Multi Function: Imported infrared probe is adopted, with 360° universal rotation, 120° sensing area and sensing distance of 3‑7m. Using high fidelity speakers, low power consumption, built in 38 high quality sound effects. 5、Security Alarm: When there is no one at home during the day and night, someone opens the door and the doorbell rings to trigger the security alarm to protect the safety of family and property. Item Type: Smart Wireless Doorbell Material: ABS Weight: Approx. 240g / 8.5oz Transmission Distance: > 200m (Open Ground) Sensing Angle: 120° Sensing Distance: 3-7m / 118.1-275.6in RF Frequency: 433MHz Ringtones: 38 One for Two: Sensors are installed in doorways and alarms can be installed in bedrooms or living rooms Power Supply of Single Sensor Head: 3 AAA Batteries (Excluding) LED Color: Blue 2 x Receiver 1 x Sensor Head 1 x Shield 1 x Fixed Head 1 x Fixed Slot 2 x Screw Spike 2 x Expansion Tubes 1 x Manual