VocoPro VHFMODULEVM1 Frequency Sets: VHF-MODULE-3: VHF A, VHF B ; VHF-MODULE-4: VHF C, VHF D 2 Wireless Microphones Included Compatible with: SOUNDMAN, CHAMPION-RV, HERO-RV Individual Volume Control for Precise Vocal Balancing. Antennas Attach Securely with BNC Connectors to Provide Clear RF Reception Not a stand-alone unit, must be used in combination with a compatible unit such as the SOUNDMAN, CHAMPION-RV, or HERO-RV)