Single 10mm Dynamic Driver with Piezoelectric Transducer -[Low & Super High] The Deepest Bass and Clear Treble Sound Various types of carefully designed drivers create rich, Hi-Fi sounds. The 10mm dynamic driver used in the Astell&Kern AK ZERO2 is meticulously manufactured using a fully automated process. This allows the driver to recreate rich and deep low frequencies. An additional piezoelectric transducer works in tandem with the dynamic driver, serving as a super tweeter that asserts its presence in the super-high frequency range that many IEMs struggle to recreate.