Wireless Bluetooth technology for an over ear headphones * High definition built in microphone * Standby time of up to 75 hours, Continuous usage time up to 8 hours * Frequency response: 20HZ-20KHZ, 40 mm Neodymium Speaker driver and Impedance 32 ohms * Rechargeable lithium ion battery 3.7V 300mA, Charging thru computer USB interface/output DC5V/500mA charge