Volume and mute fuctions on cord. I hoped that this would be an amazing wireless headset but they disconnect often and the audio cuts out frequently. And i only uses one AA battery. Had to tighten the straps fully, but they fit well enough. I am really glad that they included a second headset, which can be used as a backup headset. For the price I was impressed with the sound quality. Sennheiser is always a hit or miss between models, I just think they dont really know what they are doing. The size of the phone is perfect for my hands. To Avoid Damage; Do not tie your corset too tight when you first get it. We actually park cars in our garage and don?t have the space for a 90 degree mount.