Costway CO-10101040131 Professional VHF/FM Handheld Wireless Microphone System Frequency: VHF/FM - dual frequency design (channel a/b) - channel Frequency response: 100~1000hz (3db) - dynamic range: 80db - s/n ratio: &gt; 80db Working temperature: 32f~113f - working range: Approx. Frequency output power: 8mw (maximum 50mw) - battery (microphone): 1 x 9v (per mic) - audio out frequency power: &gt; 25mv Output resistance: 600 (unbalance) - receiving sensitivity: 30dbuv - size: 300x42x110mm