X-1 Women's Momentum In-Ear Ultra Light Headphones
I love my mementum headphones.  These cancel out the background noise, so they are great for races & running on the treadmill.  I don't like to hear people talking, coughing, spitting or huffing & puffing while I run or race - so these solve the problem!  They fit in my ear perfectly and I've never had them fall out.  Highly recommend!