Four-position gain switch (00, 01, 10, 11) can directly adjust the amplifier gain, which can be good to drive low resistance load and get more power output. Audio input: Bluetooth-compatible connection input, using CSR8635 bluetooth-compatible 4.0 module, with high device compatibility; AUX audio input convenient design, can achieve AUX & bluetooth-compatible mix output! Usage: Connect the power, wait 3 seconds until the LED blue and red light flashing alternately, you can use your cell phone or other bluetooth-compatible transceiver device to find the bluetooth-compatible amplifier, the cell phone terminal shows " SHAIBANG ", click to connect. With device memory automatic connection function. Specification: Origin: Mainland China Type: Voltage Regulator Model Number: Amplifier Board Wireless Operating voltage: 2.1 interface DC 8-25V DC power supply Audio source input: Bluetooth-compatible connection stereo input Output channel: 2 * 50w dual channel (stereo) Output impedance: 8 ohms (can drive 4,6,8,16 ohms impedance speakers) Dial switch: can be more convenient to directly adjust the rear amplifier gain, better to promote the damping of larger speakers Key functions: play/pause, next song, previous song, volume up, volume down; Color: PCB board red Power amplifier board size: 82.1mmX50.5mmX18.8mm/3.23inX1.99inX0.74in(L*W*H) Note: Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! Please allow 1-2cm measuring deviation due to manual measurement. Included: 1 x TDA7492P Amplifier Board 1. Four-Mode Gain Switch: This tda7492p amplifier boardfeatures a four-mode gain switch (00, 01, 10, 11) that allows users to adjust the amplifier gain directly, enabling better driving of low-resistance loads and achieving greater power output. 2. Bluetooth-compatible Audio Input: The power amplifier supports bluetooth-compatible 4.0 connectivity through the CSR8635 bluetooth-compatible module, providing high device compatibility and a convenient wireless audio input option. 3. Convenient AUX Input Design: With its convenient AUX input design, this amplifier allows for easy mixing of both AUX and bluetooth-compatible audio sources, enabling versatile use in various applications. 4. High-Quality Sound Performance: This audio amplifier delivers high-quality sound performance with low distortion and noise, making it perfect for music enthusiasts, audiophiles, and professionals who demand exceptional sound quality from their audio equipment. 5. Compact & Portable: Measuring only a few inches in size, this wireless audio receiver is compact and portable, making it easy to carry and use in various settings, such as home, office, or outdoors.