Easy to install, perfect match with the car Allows the addition of 2 or 4-channel amplifiers to most stereo systems without output—enables integration of amplifiers and subwoofers into existing factory systems The device has a built-in relay. When your stereo sends sound to the speakers, this device converts the speaker signal to the amplifier's input and simultaneously provides the voltage required to turn on the amplifier using 12 volts from the amplifier's power supply High-level speaker signal to low-level adapter Specifications: Applicable models: Suitable for most models on the market Color: Gray Material: ABS Size: 5.5 x 3.5 x 3 cm Package Contents: 1 x o converter Only the above package content, other products are not included Note: Light and different displays may cause the color of the item in the picture to be slightly different from the real thing. Measurement allowed error is +/- 1-3 cm