Built in Li-battery for portable use, and has USB port for recharging Contain a wired earphone, can be for wired earphone directly, or use as Bluetooth Earphone with Bluetooth receiver Round buttons, and more fit fingers, more symmetrical design, simple and elegant Control Power, Pause, Volume, Previous, Next on Bluetooth Receiver Specification: Brand : US1984 #174; 1.Bluetooth Version: 4.0 Version+ EDR Operation 2.Distance: 10M 3.Weight: 10.33g 4.Size: 50*22*15mm 5.Charging Time :2hours 6. Music Time: 5 hours 7.Talking Time: 6hours 9. Standby time: 36hours 10.Battery capacity: 120mAh If you are facing any issue in connecting US1984 Bluetooth i6S with your smartphone, please Follow the below step. This Bluetooth is different then other Bluetooth and very high quality. Pairing : Press Power Button until Blue and red Light Blink , Do not Release when blue light blink