This device combines the safety and convenience of a hands-free cell phone device with the ability to disguise your voice. One setting allows you to speak on the phone while using your hands to drive or do other tasks. When using one of the four different voice changer settings, even your closest friends will not be able to recognize your voice. Some settings sound hilarious and are great for practical jokes while others can make anyone's voice sound deep and masculine. Great for fooling your friends or to protect women and children when home by themselves. This device is universal and will work without an adapter on most cell phones- phones that have a circular plug for the 2.5 jack. This plug may be located on the side or top of your phone. You simply plug the jack into your cell phone. If you have a cell phone that does not have this type of plug you will need an adapter. Will also work on many home phones. Because most land line cordless phones also have a plug in for a hands-free headset this device will also work with them. Battery included.