The PT420 from AKG is a wireless bodypack transmitter used with the SR420 wireless receiver (sold separately) and has a frequency band of 530.025 - 559.00 MHz. The PT420 features a noiseless on/off/mute switch and a gain control for immediate volume adjustment. It comes with a AA size battery which lasts up to eight hours and has a low battery indicator to guarantee secure operation. This transmitter features a 3-pin mini XLR microphone connector and is compatible with all AKG MicroMics.