Borofone be55 tws perfect, wireless bt headphones, bt 5.1, with 1200m ah charging case, 4.5 hours of music/call, support switching between leader and follower 1. bt v5.1. chipset: jl ac6976. 2. battery capacity: 1200m ah charging case, 40m ah headphone. 3. talk/music time: 4.5 hours. Standby time: 200 hours. 4. dimensions: 78*48*30mm. total weight: 78g. 5. the headset will automatically turn on when the charging case cover is opened, support switching between leader and follower, and call siri. 6. 1200m ah large capacity charging case, can be used to charge mobile phones in emergencies. 7. the headset has a super battery life of up to 45 hours when used with a charging case.