Shure BLX Wireless Systems combine professional quality sound with simple setup and an intuitive interface for legendary audio performance right out of the box. Precision built and available in a variety of configurations, it's the most accessible way to own the stage. Rack mountable and featuring rugged metal construction, the BLX4R offers simple setup and intuitive controls. One touch QuickScan frequency selection quickly locates the best open frequency in case of interference. Removable antennas allow for quick antenna distribution. Legendary sound and performance, right out of the box.SM58 Handheld Wireless System Includes: BLX4R 1/2 Rack, Single Channel Wireless Receiver, Single and Dual Rack Mount Kit, BLX2/SM58 Handheld Transmitter with SM58 Microphone, Microphone Clip, 1/4 Wave Antennas, Zippered Transmitter Accessory Bag, PS23US Power Supply and AA Batteries.