The GLXD14UK-z2 wireless system features the linkfreq automatic frequency management system, making it easy to rely on seamless, crystal-clear audio.The system operates in the 2.4 ghz frequency band and is globally license-free. The receiver continuously analyses the available frequency spectrum, automatically linking to the transmitter to use the best set of available frequencies. If interference occurs, the receiver and transmitter intelligently move together to the best open frequencies without any audio interruption. It's as simple as that - there are no buttons to push or controls to adjust. Up to 8 compatible systems can be used in parallel. In 'automatic mode', with linkfreq mode enabled, up to 5 systems can be run. Shure's lithium-ion rechargeable batteries provide up to 16 hours of continuous use.