Shure BLX Wireless Systems combine professional quality sound with simple setup and an intuitive interface, for performance you can trust right out of the box. Precision built and available in a variety of handheld, lavalier, instrument and headset configurations, it's the most accessible way to own the stage. The BLX4R is a rackmountable version of the BLX4. It is is a half-rack sized wireless receiver built into a rugged metal chassis. It features advanced capabilities usually unavailable in wireless systems in this price range.