The system specifications 
Audio frequency response    80 ~ 10000 hz
Dynamic range      P 60 db
System distortion     1% or less
Signal to noise ratio       P 60 db
Use the distance      Appr. 25 m
Operating temperature range    5℃~ 45℃
Carrier frequency range    110 ~ 130 MHZ

.The emitter 
Frequency stability     Plus or minus 0.005%
Carrier output    10 mw or less
Stray radiation suppression.    >40 db
Modulation method      FM
Maximum modulation     Plus or minus 75 KHZ
Pickup mode     Electret capacitance.
pre-emphasis       50 mu S
Use the power supply      9 v Bat.
The power consumption      < 4