The item in question is denoted as a wireless radio frequency transmitter. It is indicated that it will either be imported as part of a wireless headphone kit or as an individual item. This ruling will address the perspective importation of the individual transmitter and not the entire wireless headphone kit. The wireless radio frequency transmitter is designed for use with either a wireless speaker and or headphone system. It is fully capable of transmitting various audio broadcast signals from various sources such as radiobroadcast receivers, televisions and household audio players. The RF signals are transmitted to either the wireless headphones or wireless speakers through the ether and not over any line connection. It operates on a frequency of 900 MHz.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/G87519