FCC certified. FCC ID:2AAR8T130; Stable signal; tour guide system transmitter adopts PLL synthesized design; with high frequency stability; less signal interfaces or statics; provides a clear; static-free transmission; Note; It can only be used with the receiver of Retekess T130 Easy to use; one way of ID setting methods; wireless and manual setting; if you have to set the ID for many receivers; the wireless ID setting method is more quickly; reduce your workload effectively Built in rechargeable battery; 900mAh lithium battery; it can last long hours upon full charge; with LCD display and battery consumption display; no any delay with your work Lavalier microphone release your hands; light weight; compact design; 58g net weight; easy to handhold; long lanyard design for the transmitter; can be hang on neck; long enough cable for the microphone easy to put into your pants pocket Support maximum 99 channels; allows 99 groups to operate simultaneously at the same place in the ran