The RS 120 Wireless Headphones system is made up of two main components - the transmitter (TR 120) and the headphones (HDR 120). Headphones can be purchased individually but transmitters are not available individually. To expand a system to have multiple headphones there are couple of options when adding extra headphones to the system.
1) Purchase an additional set of headphones (HDR 120) and tune the headphones into the existing transmitter. NOTE: The transmitter can only charge one headset at a time so the headphones would need to be placed on the base in turn to charge.
2) Purchase a second complete system (RS 120) and tune the headphones into the existing transmitter and then use the second transmitter only as a charging station.
3) Purchase a second complete system (RS 120) and have both transmitter set up and transmitting on separate channels. NOTE: This option would generally only be used when different audio sources are in use and then it is a matter of tuning the headphones to the appropriate base station to pick up the audio signal that is desired. The channel switch is a small white switch on the front of the base station near to bottom.
Here is a diagram showing the scenario with one transmitter (base station) transmitting to multiple headphones and the scenario with three different transmitters (base stations) connected to different audio sources transmitting to different headphones. NOTE: In the second scenario to change a headphone from receiving the signal from base station 1 to receiving the signal from base station 3 it is simply a matter of adjusting the TUNE dial on the headphones until the signal from the desired base station is picked up.
NOTE: Since the RS 120 is a radio frequency (RF) system the number of headphones that can be added is unlimited and the only requirement is that the headphones are in range of and tuned into the transmitter.