SONY wireless stereo headset MDR-EX750BT/L (Viridian Blue) Headphone part: Model closed dynamic / Driver unit: 9 mm dome type (CCAW voice coil adoption) / Sensitivity: 105 dB / mW (when wired connection) / code length: about 1.0m, silver-coated OFC Litz wire, removable / input plug: gold-plated L-shaped stereo mini plug Mass: (not including code) about 38g / frequency characteristic: 5Hz-40KHz / corresponding impedance: 16 Microphone part: Model MEMS / directional characteristics: omni-directional / effective frequency band: 100Hz - 8,000Hz Power: DC3.7V: Built-in rechargeable lithium-ion battery / charging time about 2.5 hours (full charge) / charging method: USB charging / battery duration (continuous audio playback time): about 7.5 hours / battery duration (continuous talk time ): between about 7.5 hours / battery duration (standby time): about 200 hours Bluetooth: communication system Bluetooth standard Ver.4.1 / Output Bluetooth standard Power Class 2 / maximum communication distance: line-of-sight distance of about 10m Accessories: dedicated headphone cable (about 1m), hybrid earpiece SS, S, M, L (2 each), micro USB cable (0.5m), Carrying pouch, clip, Japanese manual