This is a new challenge for the development, high purity gold “Au” has an ultra-high frequency range, it provides irreplaceable density and musical. AXO’s conductor includes gold and silver, we use selected silver as core, use gold by plating, it is an elegant and finest sound! AXO provides CM 2-pin, MMCX earphone spec and 3.5mm, 2.5mm and 4.4mm balance options.