Product Specifications: Product Name: Bluetooth Headset Product model: W688 Chip model: ISSC2020S Bluetooth version: bluetooth V4.1, support protocol handset\handfree\A2DP\AVRCP Transmit power: Class 2 (-6dbm - 4dbm) Communication distance: 10 meters Working frequency band: ISM band (2.402-2.480GHZ) Charging voltage: 5V Working voltage: 3.7V Battery Specifications: Rechargeable Polymer Lithium Battery (401035/120MAH) Body size: 65*17*12mm Headphone weight: 14.3g Product Specifications: Product Name: Bluetooth Headset Product model: W688 Chip model: ISSC2020S Bluetooth version: bluetooth V4.1, support protocol handset\handfree\A2DP\AVRCP Transmit power: Class 2 (-6dbm - 4dbm) Communication distance: 10 meters Working frequency band: ISM band (2.402-2.480GHZ) Charging voltage: 5V Working voltage: 3.7V Battery Specifications: Rechargeable Polymer Lithium Battery (401035/120MAH) Body size: 65*17*12mm Headphone weight: 14.3g