SM-863D is a combination of infrared transmitter and wireless headphones designed for TV. As we said, this product includes a transmitter and a chin earphone, which must be used together. The TV hearing system can only be connected directly to the digital optical, RCA or AUX audio output of your TV, DVD player, AV receiver, etc. With an additional adapter, this TV hearing system can also be connected to the coaxial, HDMI ARC and HDMI port of your TV. For more information on setup, please contact your TV manufacturer or Simolio. All connection cables, including the optical TOSLINK cable, the red/white RCA cable and the AUX headphone cable, are included. If you use an optical cable to connect, please set the TV's digital audio format to PCM or disable Dolby on your TV or streaming media. This TV headphone also has the following functions: 1. You can adjust the volume you will hear with the volume control on the headphones. However, please note that you need to feed a sufficient volume level into the transmitter base to get stable audio signal output. Otherwise, there may be dropouts or poor audio quality. 2. The transmitter also has three different audio profiles: Normal, Treble and Bass. Headphones wearers can adjust the sound to best suit their listening habits and audio content. 3. A full charge lasts for up to 15 hours.