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: PCITEM COLOR:BLUE