Driving regulations in many countries prohibit the handling and operation of a two-way radio while driving. To be able to still use an amateur radio transceiver while driving, a hands-feee kit is required which does not distract the driver and leaves the hands free for driving.
The AV-1KM hands-free kit consist of a microphone on a long goose neck, a comfortable PTT switch and a cable which is exactly matching for the radio model you use. The microphone is usually installed on the sun visor inside the car, with the long and flexible goose neck the mic can be positioned just so that it does not obstruct the view. The latching PTT switch is installed at a convenient place, for example on the gear shaft. Due to the latching function of the switch you just need to touch the switch very briefly, the hand movement is the same as when changing gears. If the radio offers a vox function, of course this can be used as well.
The hands-free kit AV-1KM comes with various cable kits, each suitable for a certain transceiver model or manufacturer type. This greatly helps an easy installation, you do not have to solder a cable of your own. The microphone is an Electret type (aka condenser type), the require supply voltage is taken from the microphone connector of the radio. This microphone type is used with nearly all FM mobile transceivers anyways. With the exact location of the microphone near the mouth, most background noise aan be avoided. The microphone gain can be adjusted very easily for best modulation. The PTT switch box offer more controls like Up/Down keys, if the radio supports such functions. A red LED signals the PTT state, this helps to avoid unintended transmissions.
The basic kit of the AV-1KM hands-free set contains the radio cable with the modular connector. This is most often used cable for FM mobile rigs. For Icom or Kenwood radios with 8 pin round (Foster) connector, an additional radio cable is required.