Features: ZK-TB21 Digital power amplifier module, BLE5.0, chip(with AM interference suppression function) , 2.1 dual channel stereo output, output power 50Wx 2 (left and right channel) + 100W (subwoofer). Multiple for protection mechanisms, with over-voltage and under-voltage, over-heating, for DC detection, short-circuit for protection to ensure its safe operation. Built-in 50x25x10mm heat sink, suitable for power supply above DC12-24V/5A, suitable for 20~100W, 4~8Ω speakers. Independent high- adjustment knob can make the sound more layered and the more shock. Bluetooth-compatible and AUX input, for almost all home audio devices, such as smartphones, MP3s, PCs, TVs, tablets, laptops, etc. Specifications: Product Name: 2.1-Channel Bluetooth-compatible Audio Amplifier Moudle Model: ZK-TB21 Bluetooth-compatible Version: BLE5.0(unobstructed, 10meters/32ft) Input Sensitivity: 500mV Input: Bluetooth-compatible+Aux Channel: 2.1-channel Adapter Power: DC12-24V/over 5A(the higher the voltage, thegreater the output power) Suitable Speaker: 20-100W, 4-8Ω Protections Mechanism: over-voltage and under-voltage, over-heating, Direct Currrent detection, short-circuit protections Output Power: ≤50W(left and right channel), ≤100W (subwoofer) Heatsink Size: 50x25x10mm Material: Metal, Printed Circuit Board Size: Approx. 118x100x22mm/4.65x3.94x0.87 inch Package Includes: 1x Power Amplifier Board Module Kit 1x Screwdriver 1x Power Adapter note: When the audio input is sufficient and the power supply voltage/current is sufficient, there will be enough output power. The higher the power supply voltage, greater the output power, the smaller the speaker impedances, greater the output power. Please ensure that power of the adaptable power supply is greater than the actual power of amplifier!