The only thing is it fell apart after only wearing it three times. Good product , good quality . Just received two of these units. Simple, inexpensive and it works. Much thinner than other socks Ive purchased from Nike. Along with your user manual you receive a quick guide which tells you about control function, ear hook replace, auto pairing and auto power off. The MIC works great. There is minimal interference with glasses. Said they looked big. I previously bought a knock off watch of this and the battery life was amazing.