DescriptionTransmitter *Radiate Frequency: FM 49.85MHz *Radiate power: max120dB *6F22(9V) battery, or used AC/DC adopter *Audio input: 500mV Headphone *Size 2450 recharge Li-ion battery , AC/DC recharge adopter *Battery recharge life: 300 cycle *Receiver frequency :FM 49.85MHz *Audio frequency response: 80HZ-15KHZ(+/-3dB) *S/N: 45dB *Out put power: 50mW *Receiver distance: 40 meter(none impediment