Feature:  Excellent quality: high quality material, safe and durable.  Protection mechanism: overcurrent, short circuit, anti-static protection.  Features: Support Wuzhi Audio APP. Modify the Bluetooth name, password setting, prompt volume adjustment, on/off prompt tone, sleep aid song, sound effect selection + custom sound effect, U disk playlist.  Wide range of uses: suitable for high quality and professional audio equipment, instruments, control circuits and telephone channel amplifiers.  It has the characteristics of small size.     Specification:  Name: 2.0 channel 15Wx2 stereo Bluetooth audio power amplifier.  Bluetooth version: 5.1.  Audio input: Bluetooth+AUX+U disk+USB sound card.  Audio output: left channel 15W + right channel 15W.  Adapter power supply: 9-24V, 2A (can not be connected to AC).  Adapter speaker: 5-30W, 4-8ohm.  Volume adjustment: multi-function knob, 360-degree stepless tuning, with volume level indication.  Single click: play/pause; double click: mode switch (Bluetooth/U disk/AUX).  Press and hold for 1 second: turn on/off; Rotate: adjust the volume.     Note:  It is recommended to use an 8?? speaker, power supply 9-24V DC, and do not overvoltage.  If driving a 4ohm speaker, the power supply cannot exceed 12V.  size: 50 x 50 x 30mm.  Material: ABS.  colour: black.     Package includes:  1 x Audio Amplifier Board Module.  1 x Screwdriver.  1 x Terminal.  Only the above package content, other products are not included.  Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.