With so much information on the internet about headset's it's hard to find the top and generally direct information. here is an article from a reputable site that i believe to be veritable, do not quote me on it but please read and enjoy
In the world of secret spy gear, a radio Communication Headsets is commonly used by undercover agents. The spy earpiece is a radio-controlled ear headphone that receives transmissions from cell phones or two-way radios. This earpiece is a small, discreet device similar to a hearing aid. The technology that enables this earpiece to work with cell phones uses Bluetooth technology.
These earpieces are connected to small wireless microphones that are hidden in the wardrobe of the agents. This gives the agent the ability to have a two-way, discreet conversation with other groups and security personnel. The Secret Service is a federal law enforcement agency in the United States that uses spy earpiece equipment as part of its work protecting public officials. These specially designed earpieces have the ability to hear wireless transmissions from radio devices that are many miles away.
A spy earpiece is typically concealed with special rubber material that looks like human skin. This earpiece is easily covered with hair and makeup, which makes it difficult to notice from a distance. Most concealed earpieces are only noticeable through behavioural actions of the users. Some examples of this type of behaviour include strange gestures and the appearance of talking to oneself.
There are many companies that sell spy equipment to the general public. This is used in daily life for surveillance and cheating. Many students attempt to use these devices to cheat on tests or college exams. They are also used by gambling rings to cheat at card games at casinos.
A police detective can use an undercover spy earpiece for surveillance operations. This tool helps an officer blend into the crowd while he monitors his suspect. It is typically hidden well enough that it is difficult for an average person to notice.
Ear headphones can also be used as spy earpiece equipment. These headphones present the illusion of listening to music when connected to an audio device. In covert operations, the music player can actually be a cell phone in disguise.
A typical spy earpiece is the same price as a standard Bluetooth ear device. This spy gear can be purchased at specialty stores or on the Internet. Most phone ear piece equipment provides good listening quality with decent wireless range.