1. Connect the positive pole of the battery, do not just connect a positive wire randomly, otherwise the circuit will burn out. 2. The GND interface must be connected to the negative pole, ground connection is OK. 3. Be sure to connect the REM interface. When testing the amplifier, you can connect it to power ground +12V. And then you should find the ACC control wire interface on your CD player, if the player does not have this interface, you can connect the ACC line found on the key switch. Make sure not to press the iron, otherwise it will short circuit. 4. If you find that the indicator light turns red when you connect the cables, disconnect the power immediately and reconnect. If the red light lasts for five minutes, the amplifier's protection will burn out. The blue light is normal. Color: black Material: aluminum alloy LED power indicator Low pass filter Input: 12V Package contents: 1 x Car amplifier 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 to differ slightly from the real thing. The allowed measurement error is +/- 1-3 cm.