Shure SLX4L Wireless Receiver with Logic Output, G4 For this wireless system component to work, please make sure your transmitter and receiver match in frequency range (style) Optional logic functionality for software echo cancellation and remote battery life monitoring (SLX4L only) SLX Wireless Systems feature the patented Audio Reference Commanding for crystal-clear sound beyond the limits of conventional wireless technology Automatic Frequency Selection Automatic Transmitter Setup 960 Selectable frequencies across 24 MHz bandwidth