Features: 
1) UHF wireless stereo headphone with 864MHz/915MHz ISM Band
2) Operation distance up to 100 meters with latest UHF/RF wireless technology 
3) Several headphones can be used simultaneously with one transmitter 
4) Built-in 40mm mylar speaker 
5) Auto mute and auto tuning function available for headphone
6) Active noise reduction system for crystal clear sound
7) PLL system for ultimate frequency stability

Specifications: 
1) System: UHF/RF 
2) Carrier frequency: 
    a) For Europe: 863.5, 864, 864.5MHz 
    b) For US: 914, 914.5, 915 MHz 
3) Modulation: FM 
4) Mode: stereo 
5) Transmit power: ≤10mW
6) S/N ratio: ≥75dB 
7) Channel separation: >35dB 
8) Distortion: <1% 
9) Frequency response: 30 - 20,000Hz
10) Power supply of transmitter: DC12V 150mA
11) Power supply of headphone: 2 AAA batteries