Feature:1. This Bluetooth audio 2.1 channel power amplifier module has two audio input methods, AUX and Bluetooth, two in one. The 5.0 Bluetooth version has higher transmission efficiency and longer transmission distance.2. The Bluetooth audio power amplifier module has 2.1 channels and the maximum output power is 2X50W+100W. With antenna and antenna base, the signal is better, the efficiency is high, and the anti‑interference ability is strong.3. This power amplifier module has short circuit protection, overcurrent, overheating, and anti reverse protection to prevent complete failure. When an overload occurs, the device reports the fault condition to the processor to protect itself from damage.4. It adopts copper DC connectors and barrier terminals. It can withstand high current without heating or damaging wires. No DC head lead, compatible with the input power interface of this product, even if you don't have a DC head adapter or battery, you can easily wire it.5. Provides a stable and fast connection with a wide range of compatibility. Easy to install and use. With bass, treble, subwoofer frequency and volume control, it is widely used in shop solicitation, home theater, quadrate speakers, etc.Specification:Item Type: Power Amplifier BoardMaterial: PCBModel: ZK-MT21Bluetooth Version: 5.0 (Approx. 15m/49.2ft without Obstruction)Audio Input: AUX + BluetoothNumber Of Channels: 2.1 ChannelsInput Sensitivity: 500mVAdapted Power Supply Voltage: 12-24V/5A or More (Do Not Connect 24VBattery Pack)Speaker: 20-100W, 4-8ΩOutput Power: Maximum 50W (left and Right Channel), Maximum 100W (Subwoofer)Protection Mechanism: Anti reverse Connection, Overheating, Overcurrent, Short Circuit ProtectionPurpose: Digital Power Amplifier Board.Package List:1 x Power Amplifier Board Module2 x Acrylic Board1 x Screwdriver9 x Screw4 x Brass Connecting Rod4 x Brass Terminal5 x Knob1 x Round Hole ConnectorNote:1. The power switch on the board is a standby switch. After the switch is turned off, the machine is in a low‑power standby state. Turn off the power completely or unplug the DC plug on the machine for a long time.2. Please use a power adapter with sufficient power to connect to the power amplifier board, otherwise the sound will be distorted.