1. The energy storage capacitor is increased, 4700ufx2+470uf, the sound from the stereo and especially the subwoofer is stronger. 2. Output LC filtering, the use of film capacitors has better filtering effect, no sound is emitted from the inductor, and the waveform restoration is better. 3. The volume of both stereo and subwoofer can be adjusted separately, and the adjustment range is . Using a -level Bluetooth chip, the parsed audio delay is smaller and clearer. 4. Supports the Bluetooth pairing function. After using the function, two sets of power amplifiers can be paired to become stereo. Connect to APP, can support remote firmware upgrade or firmware refresh, easy to upgrade and perfect product function. 5. Added power-down circuit to reduce sound. Increase the heat sink, the heat dissipation effect is better. Model: TB22 chip:TPA3116D2 Input Mode: Bluetooth Work Voltage: DC 12V-24V(Above 2A) Channel: 2.1 CH Stereo Output Bluetooth version: Bluetooth 5.1 Bluetooth transmission distance: 10m(If you need to go further, please connect the antenna yourself) MAX Power Output: 50W x 2 +100W type:Amplifier Board size: 121 x 100 x 26mm Material: plastic colour: black Package Contents: 1 x TB22 Bluetooth Amplifier Board 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.