Fangrui Product Details Eliminating Buzzing Noise Caused By Ground In Some Car Speakers / Home Stereo Systems. No External Power Supply, This Noise Isolator Can Achieve A Clear Speech/music By Eliminating The Current Noise In Some Car Speakers / Home Stereo Systems. Works With Any Portable Device That Has 3.5mm Jacks, For Your Car System/home Stereo. Compact And Lightweight, It Will Not Take Much Space And Can Be Easily Taken Away. Item Type: Ground Loop Noise Isolator Interface: 3.5mm Frequency Response: 20hz-20khz Input: Stereo Size: 59 X 20 X 18mm Material: Plastic Colour: Black Package Contents: 2 X Ground Loop Noise Isolators / 4 X Ground Loop Noise Isolators 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.