Car Home Stereo 2 Channel Auto 12V Pre-wired Radio Audio Power Noise Filter System Ground Loop Isolator Filter Suppressor Audio Description: The Car Power Filter will bring you a good audio effect. There are 3 wires. Blue wire for input (12V), Red wire for output and black wire is groundwire. it is a stable and wear-resisting little tool for noise cancellation. Feature: Power supply noise of igniter produces filtration effect, make the sound effect is better. Specification: Material: Plastic,Metal Voltage: 12V Package Includes: 1 Piece Car Noise Audio Filter Isolator Note: Please allow 0.5-1 inch difference due to manual measurement.(1 inch=2.54cm) Please check the size measurement and the picture carefully before making payment. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Please understand,Thank you.