1. TDA7492P Bluetooth Power Amplifier Board 2. Bluetooth Audio Receiving Amplifier Bluetooth CSR4.0 Digital Amplifier Board Bluetooth 3. The Dip Switch Makes It Easier To Directly Adjust The Gain Of The Post-Amplifier And Better Promote Speakers With Larger Damping. 4. For Professional Use 5. Need A Professional To Install The Corresponding Accessories To Avoid Damage To The Accessories Power Supply: 2.1 Interface DC 8-25V Power Supply Audio Source Input: Various Versions Of Bluetooth Connection Stereo Input, Using Csr8635 Bluetooth Chip, Bluetooth V4.0, Extremely High Software Compatibility Output Impedance: 8ohm Is Better (Can Drive 4, 6, 8, 16 Ohm Impedance Speakers) Output Power: Add The Preamplifier 5532, The Output Power Is Sufficient Note:Different Batches May Have Differences In Product Appearance, Color, And Printed Characters, Which Not Affect The Use Colour:As Shown Material:PCB and Plastic and Silicone Package Contents: 1 x Power Amplifier Board Module 4 x Base Silicone Plug 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. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.