CYMUM CY-15 HiFi Portable Headphone Amplifier For iPhone 7 To 3.5mm Adapter Earphone Amplifier Smartphone Audio Amplifier (Silver) CYMUM HI-FI AUDIO AMPLIFIER No charge No battery,use as adapter to change lighting to 3.5mm for iPhone Come with micro USB adater cable,can use on other smartphones too. High performance headphone amplifier chip Advanced stainless steel processing and cutting