The infrared doorbell has an effective sensing distance of 4 meters and will play a preloaded sound when someone enters the detection range. Audio files can be customized by connecting the device to a computer via USB cable and copying new MP3 format audio files to the player. MP3 files will play automatically when the PIR sensor is activated. (Note: It is compatible with Win7/XP computers but may not be recognized on Win8/Win10 systems). Ideal for retail environments, the device emits a warm welcome message, greeting prompt, warning alert, or voice advertisement upon detecting human movement. Different audio files can be loaded based on specific application needs to achieve the desired effect. Power options include 3 AAA batteries (not included) or connection via the Mini USB port for external power supply. (Note: Audio replacement is not supported through the Mini USB power connection). Features a practical security function: when leaving the store, switch to alarm mode to detect and alert ing individuals, helping to deter potential intruders. Designed with memory functionality—selected audio and volume settings are retained even after the device enters sleep mode or loses power. Specifications: Model: Microsound V22.12 Product Type: MP3 Infrared Doorbell Audio Format: MP3 (Bit Rate: 8–320Kbps), high-quality sound with two volume levels: low or maximum Built-in Speaker: 8ohm 1W speaker Sensor: Infrared induction with automatic detection Power Supply: DC 3V–5V stabilized voltage Working Current: 100uA (Sleep Standby Mode); 130mA (DC 4.7V) (Playing Mode) Infrared Detection Distance: 4 meters (45° angle) Sample Rate: 14KHz Memory: Built-in 4Mbit SPI FLASH memory Installation: Ceiling or wall mount Power Source: External USB power supply DC 5V or 3 AAA batteries (not included) Working Current: 100uA (Sleep Mode); 60mA (Playback Mode) Humidity Range: 10–85% RH Color: White Material: ABS Dimensions: 90 x 60 x 26.6mm Package Includes: 1 x Audio Doorbell Note: The package includes only the items listed above. Lighting and display differences may cause slight color variations between the image and the actual product. Measurement tolerance: ±1–3cm.