The Shure Performance Gear PGX4 Wireless receiver makes wireless setup a snap. With features like Automatic Frequency Selection and Automatic Transmitter Setup, the PGX4 offers the best in wireless to performers on the go. The PGX4 was designed for use with PGX Wireless Systems. The PGX Wireless Systems feature Shure's patented Audio Reference Companding for crystal-clear sound beyond the limits of conventional wireless technology. Shure professional wireless systems deliver legendary sound quality, stage-proven durability and hassle-free setup for worry-free performance.