1000m connecting distance for two riders; daily water resistant; auto change between phone call and intercom; it can pair with cellphone GPS and other stereo devices at the same time; supports monitoring phone calls on it redial last contacted number; can play audio files from GPS SBC MP3. With play / pause next / previous stop key; good echo / noise delimination. How to use: connect the earphone to the intercom and press the power switch till red / blue LED flashes; click the power button on either one of the earphone to activate pairing (blue LED flashes)