Features:Single Track.Portable behind-the-head wearing design, convenient for sports.Allow you answer or reject phone calls anytime and anywhere.Built in Microphone for Handsfree Cell Phone use or chatting on QQ, MSN.Built-in lithium battery (charged via USB).Specifications:Bluetoooth

Features:Single Track.Portable behind-the-head wearing design, convenient for sports.Allow you answer or reject phone calls anytime and anywhere.Built in Microphone for Handsfree Cell Phone use or chatting on QQ, MSN.Built-in lithium battery (charged via USB).Specifications:Bluetoooth version:Version 2.1Frequency: 2.4 - 2.48GHzSupport format: MP3 WMATalk time: Up to 4 HoursCharge time: 2 hoursPower source: Built-in Li-ion Battery (USB  Charging)System requirement: Windows 98 or aboveMaterial: PC