Shure BLX4 Single Channel Receiver, J10 Microprocessor-controlled internal antenna diversity One-touch QuickScan frequency selection quickly locates the best frequency 1/4" and XLR audio outputs; Two color audio status indicator LED Not all channels are useable in every area of the United States. This Receiver and microphone combo require the user to set the correct useable channel to avoid any drop outs. Consult BLX Channel guide to select compatible channel sets For this wireless system component to work, please make sure your transmitter and receiver match in frequency range (style). Up to 12 compatible systems per frequency band (region dependent) Up to 12 compatible systems per frequency band (region dependent), One-touch QuickScan frequency selection quickly locates the best frequency, and Microprocessor-controlled internal antenna diversity. XLR and &#034; output connectors. Two-color audio status indicator LED (Green:Normal audio levels / Red:Excessive audio levels)