Infra red set-top receiver includes con block and Power Supply 

External Remote Sensor

If any Harman Kardon product is placed behind a solid or smoked glass cabinet door, the obstruction may prevent its remote sensor from receiving commands. In this event, the optional HE 1000 external remote sensor may be used. If other components are also prevented from receiving remote commands, only one sensor is needed. The HE 1000 can also be used as optional remote sensor in the remote room in multiroom installations.