This is a Nicestuff AD869 or 68869 carkit-specific adapter for use with their NSD-series, EZ-series and PR-series carkits integration harnesses. The black 24-pin connector on this adapter is designed to plug directly into the Parrot MKi-series of carkits - the MKi9100 and MKi9200. It is also compatible with the Motorola TK30 carkit. When used with a vehicle-specific adapter harness (see the other items in my booth for a selection of harnesses), on activation of the Mute line by the carkit, the vehicle audio will switchover to the handsfree kit. This adapter directs supply of the following connections to the carkit: VBATT - constant +12V power supply Ground - chassis ground Ignition - switched +12V signal Mute - active-low trigger Mute connection Speaker (+) - differential mono audio signal from the carkit or device Speaker (-) - differential mono audio signal from the carkit or device It also provides a convenient L/R RCA audio connection for integration the carkit stereo music playback audio into the vehicle stereo through an Aux input. This allows the carkit to utilize all the features and power of the factory radio for music playback, rather than relying on the (typically) less powerful amplifier in the carkit. I have a mobile electronics installation business and am selling off some excess inventory. Please feel free to send a message if you have further questions about any of my items. Thanks for looking!