For severe to profound hearing loss. Do you have severe to profound hearing loss and do not want to spend on an expensive high powered behind-the-ear hearing aid? Do you have a behind-the-ear that causes too much feedback or squealing? Then the body hearing aid is for you! The body hearing aid does not suffer from the feedback or squealing issue that behind the ear hearing aids do because the microphone (the box) is attatched to your clothing while the reciever is in the ear. This makes is very difficult for the sound produced by your hearing aid to make it back to the microphone and cause feed back. This hearing aids can either use tips or molds if you have them. Takes a AA size battery.