TX=Transmitter, RX=ReceiverThis HDMI extender built-in wireless transmission protocol, it can wireless transmit HD audio and video signal at the same time. Warm Tips :1. Pls use this product in a barrier-free open space, do not go through barriers, because the barrierswill block signal transmission, if need to use go through barriers, pls contact us to buy our 200m version.2. Both TX and RX cannot work alone, pls buy at least 1 TX and 1 RX as a set then you can use them.3. With the increase of RXs, or the barriers, the wireless transmission distance will be shortened.1 TX to 1 RX : max. 50m;1 TX to 2 RX : max. 30m;1 TX to 3 RX : max. 20m;1 TX to 4 RX : max. 10m; The final distance shall be subject to the actual use. Features:1. HDMI video and audio transmission via built-in wireless transmission protocol, no need wifi or internet2. HDMI 1.3, HDCP1.2 compatible;3. Support regular HD video resolution up to 1920x1080 ;4. The transfer is efficiency to ensure that the playback