I bought these noise filters do to a buzzing in speakers and alternator whine. I've never owned any b4 and these are my first. Had them hooked up and alternator whine was gone and buzzing wasn't as noticeable. After a month i think i cooked the inside of them because everything came back. I have two for each amp. 4 ch powerbass600w and 1 ch planetaudio 4000w. I like my music loud so maybe they couldn't handle it.