1.Please connect the battery positive,Don't just connect a positive line casually, or it will Burn out circuit. 2.The GND interface must be connected to the negative pole,ground connection is OK. 3.Be sure to connect the REM interface.when you test the amplifier,you can connect with power ground +12V.And then,you should find the ACC control wire interface which on your CD player, if the Player has no this interface,you can connect the ACC line that on the key switch.Make sure don't Press the iron, or it will short-circuit. 4.If you find the indicator light is red when you wiring,please unplug the power immediately and reconnect.If the red light lasts for five minutes,the protection of the amplifier will burn out.The blue light is normal. Colour:black Material:aluminum alloy LED power indicator Low pass filter Input:12V Package Contents: 1 x Car Amplifer 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.