Bluetooth 4.1 and Universal Intercom Crystal-clear HD audio and Advanced Noise Control Working Intercom distance- up to 1.6 km (1.0 mi) in open terrain. Supports up to 4 riders. Battery Charging time- 3 hours. Talk time- 13 hours Pair with other Sena products for easy rider to rider communication Smartphone pairing for music, GPS, and phone calls.