I bought the shoes for my granddaughter. I prefer a bit warmer tone and this app achieved that easily. They stay in place, handle all the sweat I can throw at them, have great battery life, and dont lose connection no matter where, in my Jersey, I keep my phone. The quality of the material I think is the problem. In fact, in my first pair of these shoes, I put holes and grommets near the rear to lace them up my leg Iike ballet dancers toe shoes to prevent any flopping. These slippers fit well and seem well made. I have been using these for over a week now and so far I have found no issues. I will definitely purchase from this brand again. I still give Sony a slight win in this department. Im sure as time goes on the shoe will stretch and this wont happen or Ill just learn to deal with it.