This Sennheiser SR 300 IEM wireless transmitter operates in the 630 - 662 MHz frequency range. Note that it doesn't come with a power supply. Due to its frequency range, it's not legal for use in the U.S. Always check your country's wireless frequency laws before buying. Also, this unit has only been power - tested and doesn't include antennas.

Using this Sennheiser SR 300 IEM wireless transmitter is straightforward. First, make sure you have a suitable power supply as it's not included. Connect it to your audio source according to the general connection method for wireless transmitters. Before using it, double - check your country's wireless frequency regulations to ensure legal use. When it comes to maintenance, keep it in a dry and clean place. Since it doesn't have antennas, be extra careful not to damage the connection ports. If you encounter any issues, consult a professional for help.