Bluetooth Version: V4.0Bluetooth range: 10 m (free space)Transmission frequency: 2.402 GHz-2.48 GHzBluetooth profiles: HSP / HFP / A2DP / AVRCPHeadband Material: metalDriver units: 40mmNoise reduction value: 18dB-20dBMic Size: 4.0 * 1.5mm for hands give callCushion set Size: protein material, 9.5 cm (L) * 8 cm (W)Wear case: cloth materialAux cable length: 1.5 mBattery capacity: built-in 400 mAh lithium batteryCharging voltage: micro usb 5 V / 1AFull charging time: about 2 hoursWorking time: over 20 hours, if ANC away from / over 18 hours, if ANC on