Features: Only support to play MP3 audio, two levels of volume are optional. Human body induction, induction distance up to 4 meters. Built-in 81W speaker, built-in 32Mbit (4Mbyte) flash memory. Two playback modes: full loop playback, single loop playback. Press the A button to play the previous audio and the B button to play the later audio. Download audio files from your computer via the USB interface. Power supply mode: three AAA batteries or USB power supply. Specifications: Condition: Brand New Material: ABS Color: White Power Supply: USB/3 x AAA batteries (excluded) Audio: Only support MP3 Volume: Two levels Detection Distance: Maximum 4m Speaker: Built-in 8 1W speaker Memory: Built-in 32Mbit4Mbyteflash memory Memory Expansion: Not Support Package List: 1 x Motion Sensor Doorbell 1 x Bracket 2 x Stickers Package List 1Only support to play MP3 audio, two levels of volume are optional. 2Human body induction, induction distance up to 4 meters. 3Built-in 81W speaker, built-in 32Mbit (4Mbyte) flash memory. 4Two playback modes: full loop playback, single loop playback. 5Press the A button to play the previous audio and the B button to play the later audio.