Specifications: Frequency Response: 50 - 15,000 Hz; Dynamic: 110 dB; RF Frequency Range: 210 ~ 270 Mhz; Operation Range: 200 Ft Adverse Condition , 800 ft line of sign; Current consumption: 25mA; Lower Battery Indicator; Power On/ Off Mute; Volume Control; Frequency Steadying: Less than 0.002%; Modulation Mode: FM. Package: 4 VHF Wireless Microphones; 3ft 1/4" to 1/4" Microphone Cable; 4 x (9V) batteries; Manual book. If you order 2 or more set, please call us and we can select difference frequency systems to fit your requirement.