Mi Quad Driver In-Ear Headphone is a high-end earphone for music lovers and audio fans. It is equipped with two speaker drivers and two balanced armature drivers. It delivers an accurate sound and restores original sounds to bring natural lifelikeness, offering a superlative audio experience. The main body is made of zirconia ceramic material and silver-plated wire for a premium look and feel. A Bluetooth 5.0 dongle lets users choose between using the earphones with or without wires. a whole brand new experience for this kind of earphones.