Engineered for professional live sound: Rugged all-in-one wireless monitoring system for in-ear applications. Robust bodypack receiver and reliable in-ear monitoring IE 4 headphones delivering clarity along the whole frequency spectrum for daily use on stage Half-rack stereo transmitter in a full-metal housing with OLED display for full control Easy and flexible wireless synchronization between transmitter and receiver via infrared Compatible with Sennheiser WSM control software for flexible frequency allocation Up to 16 compatible channels Up to 42 MHz bandwidth with 1680 selectable frequencies, fully tunable in a stable UHF range Transmission Range: up to 100 meters / 300 feet High RF output power (up to 50 mW) depending on country regulations.