Equipped with high-quality electronic components. Supports up to 20 hours super long working time. One button for mono / stereo audio channel exchange. 16 sound level can be adjusted. Comes with separate AUX input port, MIC input port and key lock function. Adjustable frequency 60-108MHz, can also set to fixed frequency. Speciallized antenna with stable transmission signal up to 500 meters. Suitable for tourist guide, training course, traveling, study activities, etc. Note: The transmitted signal be affected by the surrounding environment, and the launch distance be limited. Frequency Range: 60-108MHZ Frequency Stability: 10PPM Frequency Response: 50Hz-1500Hz Distortion Degree: 1% SNR: 60dB Suppored Format: MP3 Power Supply: BL-5C 3.7V 1000mAh Color: Black Material: plastic Package Contents: 1 x audio transmitter 1 x antenna 1 x USB data cable 1 x 3.5mm audio cable 1 x English instruction manual Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.