Shure SLX 1 / L4E SLX-Series Pocket Transmitter - display with group, channel and battery, infra-red frequency transmission from the receiver, 960x switchable frequencies, lock for menu and on-off switch, 2x 1.5V batteries, TQG-plug for microphone or instruments, frequency range: L4E 638-662 MHz, up to 7 systems parallel. Please note: Due to every country having different regulations, you may need to Contact your local licensing authorities before using a wireless system.