The GLXD4 Digital Wireless Receiver from Shure is designed to work with Shure's GLX-D series digital wireless systems. It operates on Shure's Z2 frequency band between 2400 and 2483.5 MHz on a 2.4 GHz ISM wireless band. Shure's proprietary LINKFREQ automatic frequency management, which scans for clearest available frequency range, will automatically link the GLXD4 and a compatible transmitter. The GLXD4 has continuous interference monitoring and will automatically switch frequencies to avoid interference and drop outs. The integrated battery charging station allows you to charge your transmitter when not in use, or a back-up battery pack while in use. Your transmitters remaining battery life is displayed on the GLXD4's front-panel LCD screen. Up to 8 systems can be used simultaneously.