Product name: 2.1 channel Bluetooth audio amplifier module Material: PCB+metal Product : -LT21 Bluetooth version: 5.1 Audio channel: 2.1 channel Color: Black Input mode: Bluetooth+AUX+USB+USB sound card supply: above DC9-24V/3A Audio output: left channel 15W+right channel 15W+subwoofer 30W Adaptive horn: 10W-50W/4 - 8 Output : 15W x 2 (left and right channels)+30W (subwoofer) Volume adjustment: high-end encoder knob adjustment, smooth feel Protection mechanism: overheating, overcurrent, short circuit, anti-static protection Special function: support Audio APP control Product size: 75 x 60 x 22 mm Product weight: net weight 66g Note: It is recommended to equip an 8 horn with supply of 9-24V DC. Overvoltage is not allowed. If the 4 horn is driven, the supply cannot exceed 12V. Package Contents: 1 x -LT21 amplifier board 1 x DC adapter 1 x screwdriver Only the above package content, other products are not included. Note: Light reflection and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.