Protective Function - Over-voltage Protection, Under-voltage Protection, Over-heat Protection, Short-circuit Protection, This means that the Bluetooth amplifier board is not easily . Etremely low noise, quality, etremely low distortion, protecting your for original-sound eperience. Transparent sound, fast low-frequency response, strong mid frequency teture, high frequency smoothness, and minimal loss. Thickened heat sink, silent and long-life fan; Solved the heat dissipation problem and better utilized the advantages of high power. Multiple audio input methods - The amplifier offers multiple input methods, including Bluetooth, AU, USB flash drive, and USB sound card input. This versatility allows you to connect it to audio sources such as smartphones, computers, MP3 players, and more, ensuring compatibility with your preferred devices. Model:-301B Name:Mono 30W Bluetooth audio amplifier module Power amplifier chip:domestic chip Bluetooth version:5.3 Bluetooth transmission distance:15 meters Audio input:Bluetooth +AU+U disk +USB sound card Audio output Mono:30W Power supply:DC9-24V, 3A (no AC) Adaptive horn:4-8Ohm, 5-30W Colour:Black Material:PCB Package Contents: 1 * Audio Amplifier Board 1 * Screwdriver Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.