Wireless B20 listening to music with FULL, DEEP BASS and RAZOR SHARP HIGH END and Noise Cancellation Technology MICROPHONE AND VIBRATING CALL ALERT the built-in microphone makes it possible to use the Headphone for Phone calls, Skype, youtube, Gaming and much more. Wireless version 4.2 Operation distance 10m Range of Frequency 2.4 t0 2.8GHz ISM band sensitivity 85(dB) PC interface USB 2.0 Music format MP3/WMA TF card support 128M-32GB FM frequency 87.5-108MHz Rechargeable lithium battery 250 mAh Headphone specification Type Stereo headphone with MIC Speaker 40mm Sensitivity 115(dB) S.PL at 1khz Impedance 32 Frequency response 20HZ to 2-0 KHZ Rated power 40mm power capability 100mW cable Length 1.5m Microphone unit 4.5mmX2mm – 58dB-3dB Plug Type 3.5mm stereo. Allow you to enjoy digital-quality music wirelessly and convert between music and phone calling mode freely. Support TF card Support FM can receive high-quality stereo radio. Support wireless stereo devices to receive A2DP stereo music from laptop computer, desk computer, tablet PC, iPhone, Blackberry, wireless adapter, MP3 player or anyother device that supports wireless stereo audio.