Car Home Stereo 2 Channel Auto 12V Pre-wired Radio Audio Power Noise Filter System Ground Loop Isolator Filter Suppressor 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