Also helps with the noise isolation. I now will be calling Amazon Customer Service. they work perfectly fine. But it is cool is that I am hearing her through both buds! I have faith that once I brake them in they will be my favorite goto shoes. Lovely mini-mini power extension. She uses them primarily for her swim class. The noise isolation with the proper sized ear fitting is very good. The seller I purchased from, SSA DISTRIBUTORS INC. This is that case.