Wireless Headphones,Sufum In-ear Earbuds Bluetooth Headset Sport Bluetooth Earpieces for Cell Phones (Black) It provides clear sound with CVC 6.0 intelligent noise reduction, CSR 4.1 Chip and MIC. Sweatproof & waterproof Design makes it perfect for use in sports/running/gym/exercise and other outdoor activities; the flat cable avoids winding and knotting; Built-in battery allows long playing time and only 1-2 hours to charge (headphone battery power can show on phones with IOS). With Bluetooth 4.1 version, it is compatible with almost all Bluetooth-enabled smart phones and other devices; it can even work with two phones simultaneously. Its comfortable in-ear design and it consists of metal earbuds & soft silicone rubber caps; the magnetic tip on the back of the headphones helps the earbuds stick with each other when not used.