Professional grade circuit for ultra-low distortion and low noise Pairs of power work can use two AAA batteries Can use outer direct current power as rechargeable battery LED frequency points out, adopts the lightning way frequently of 2Hz Frequency: 14 different frequency (preset 4 frequency), switch by the side Frequency range: 87.7 to 107.9MHz Effective distance: more than 10m Audio response: 50 - 15,000Hz Power supply: DC12V Operation temperature range: 0 to 40deg. C