AKG Pro Audio WMS420 Head Set Band U2 Wireless Microphone System Detachable receiver antennas enable the use of professional RF accessories C555 L high-performance head-worn condenser microphone is ideal for handsfree applications Transmitters with charging contacts saves money in day-to-day use and preserves the environment Compatible with all AKG Micromics almost all applications can be covered Low battery warning indicator for secure operation