The Aerpro APUSBD4 USB / HDMI Extension Adaptor provides a professional and discreet solution for accessing the rear USB and HDMI inputs on an aftermarket AV headunit in your vehicle. With an easy to install plug and play design, it features a circular grommet mounting system to ensure a seamless and tight connection. Position the USB / HDMI ports and twist the rubber mount to lock in place. Once installed, the USB and HDMI ports will enable compatible devices to connect with the aftermarket headunit.