Westone ES20 Dual Driver Balanced In-Ear MonitorsWestone Custom Fit Technology Fully custom earpieces are cast, sculpted, and polished by hand from actual impressions of your ears, resulting in the best fit and acoustic seal possible. Balanced Armature Westones balanced armature driver is significantly more compact and efficient than a traditional dynamic driver. Westone monitors provide enhanced sonic detail and frequency range that extends well beyond typical in ear solutions. Flex Canal A body