Bluetooth: Bluetooth 4.0Bluetooth protocol: support A2DP1.2, HFP1.6, HSP1.2, AVRCP1.4Transmission distance: about 10mInterface: Micro-USBKey Description.:1. Touch buttons: volume +; volume; previous song; next song; BluetoothRight key; 2. Power keyIndicator light:1. Red touch indicator (volume +; volume-; previous song; next songSong); 2. Blue touch indicator (Bluetooth pairing, pause / resume, connectListen / hang up); 3. Red power indicator (charging process, low battery alarmNote); 4. Red breathing lightTheoretical power: 1.8WInput power: 4.75V-5.25VCharging time: 4 hours