A Ultra High Frequency Wireless microphone with rechargable receiver. (this avoids having to use another box with arials and additional power supply.
Simply plug into any microphone input and enjoy cable free singing with any karaoke machine
The wireless range is up to an impressive 50 metres, the recharging is by a convenient USB port and lasts approx 8 hours.
The Wireless Microphone itself is powered by AA batteries which are inexpensive to run and again give a running time of approximately 8 hours of use.