BT 4.1+EDR. Airoha AB1512. Comfortable in-ear design with sweatproof function. 6mm loudspeaker with perfect sound effect. Built-in clear microphone to guarantee high-quality calls. Micro USB charging port. Built-in 100mAh rechargeable battery. Working time: up to 4-5h. Standby time: up to 250h. Connect two BT devices simultaneously. If it connects with IOS system, it will show battery status.