This infrared doorbell has a 4-meter effective sensing distance and plays a pre-loaded sound when someone enters the area. Customize the sound! Simply connect to your computer via USB and copy new MP3 audio files to the player. Your MP3 files will play automatically when the PIR sensor is activated. (Note: Recognizable on Win7/XP computers, may not be recognized on Win 8/10 computers). Widely used in stores: Provides a warm welcome, greeting prompt, warning prompt, or plays voice advertisements when it detects someone passing by. Download different sound files for various applications to achieve the desired effect. Dual power supply options: Equipped with a 3 * AAA battery compartment and Mini USB port. Power it with 3 * AAA batteries (not included) or the included Mini USB charging port. (Note: Does not support sound changes via Mini USB). Practical anti-theft function: When leaving, switch to alarm sound mode. The recording player can detect and warn people approaching, deterring thieves. Unique design: Supports memory function. Once you select a sound and adjust the volume, the device remembers your settings even after power off. Specifications: Model: Microsound V22.12 Product Type: MP3 Infrared Doorbell Audio Format: MP3 (Bitrate: 8 ~ 320Kbps), two volume levels: small or maximum. Built-in Speaker: 8ohm 1W Speaker Sensor: Infrared induction, supports automatic induction Power Supply Mode: DC3V ~ 5V Stabilized voltage supply Working Current: 100uA (Sleep Mode); 130mA (DC 4.7V) (Playback Mode) Infrared Induction Distance: 4 meters (45d Angle) Sampling Rate: 14KHz Memory Size: Built-in 4Mbit SPI FLASH memory Installation: Ceiling mounted Power Supply: External USB power supply DC 5V or 3 AAA dry batteries (not included) Working Current: Sleep mode 100uA; Playback mode 60mA Humidity: 10 ~ 85%RH Color: White Material: ABS Size: 90*60*26.6mm Package Contents: 1 * Sound Doorbell