The HEX70ARCKIT 4K HDBaseT™ ARC extender set offers market leading features for the custom installation industry. The product delivers HDMI, ARC, Optical Audio Return, Bidirectional IR and Bidirectional PoC (Power over Cable) up to lengths of 70m (40m at 4K 60Hz 4:2:0). Advanced Audio Return Channel (ARC) Functionality The three modes for Audio Return and CEC are controlled using the switch located on the Receiver unit. The switch positions are HDMI, PASS or OPT. See below for explanation: HDMI HDMI ARC in to the Receiver from the display, to Optical Out and L/R Out on the Transmitter. CEC communication over HDBaseT™ is blocked. PASS HDMI ARC in to the Receiver from the display to HDMI ARC, Optical Out and L/R Out on the Transmitter. CEC communication is passed through the HDBaseT™ link. OPT Optical audio in to the Receiver from the display, to Optical Out and L/R Out on the Transmitter. CEC communication over HDBaseT™ is blocked.