Features: brand new and high quality Audio input: BT+AUX+USB+USB sound card. Audio output: left channel 15W + right channel 15W + subwoofer 30W. for Protection mechanism: overheating, overcurrent, short circuit, anti-static for protection. Features: Support Wuzhi Audio APP. Modify and change the bt name, password setting, volume adjustment of prompt sound, on/off prompt sound, sleep aid song, sound effect selection + custom sound effect, U disk playlist. Note: It is recommended to use 8Q speakers, power supply 9-24VDC, and do not overvoltage. If driving 40 speakers, the power supply cannot exceed 12V. Specifications: Material: Metal Color: As the Picture Shows Net Weight: 102g/0.22lbs Note: Please allow 1-2cm errors due to manual measurement. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1PC ZK-LT21 Digital Power Amplifier Board