WL-2002 Infrared wireless stereo headphone Two channel Ergonomic design for comfortable wearing Auto mute and auto power off function on headphone Carrier frequency: a) A channel: 2.8MHz for right channel; 2.3MHz for left channel b) B channel: 3.8MHz for right channel; 3.2MHz for left channel Speaker: 40mm mylar Effective range (maximum): about 10 meters Power source: 2 x AAA batteries Battery life: about 48 hours