This Sennheiser EM 3031-U Microport Receiver operates in the 720 - 756 MHz frequency range. Note that due to the frequency, it's not legally usable in the U.S. Always check your country's wireless frequency laws before buying, as some frequency ranges may be illegal depending on the country. The unit has only undergone a power test. It comes with the correct power supply.

Using this Sennheiser EM 3031 - U Microport Receiver is easy. First, connect it to the correct power supply that comes with it. Then, you can start using it for your wireless audio needs. But remember, before you buy and use it, check your country's laws about wireless frequency usage. Since it operates in the 720 - 756 MHz range, it might not be legal in some places, like the U.S. As for maintenance, keep it in a dry and clean place. Avoid exposing it to extreme temperatures or humidity. If you have any issues, you may want to consult the Sennheiser support team.