The Sennheiser ew IEM G4 Wireless Monitor System (A1 Band) is an industry-standard, professional in-ear monitoring package engineered for live stage, theater, and broadcast applications. Operating over the clean, low-UHF A1 frequency band (470 to 516 MHz), it delivers a highly stable RF transmission footprint with exceptional audio clarity across a generous 100-meter (300-foot) line-of-sight range.