JQ 4U 10mm Beryllium Diaphragm Driver HiFi In-Ear Earphone with Handcrafted Shell, Detachable 0.78mm 2Pin 5N OCC Silver-plated CJQ 4U 10mm Beryllium Diaphragm Driver HiFi In Ear Earphone with Handcrafted Shell, Detachable 0. 78mm 2Pin 5N OCC Silver plated Cable 10mm Beryllium Diaphragm DriverAs we know, adopting Beryllium driver minimizes the audible ringing and distortion heard from traditional metal diaphragms (e. g., titanium or aluminum). Beryllium enables an extra octave of useable, non resonant high frequency energy pushing breakup modes beyond the audible band. JQ 4U