Though 500K can be used to listen to music, it’s clearly not optimized for that purpose. Rather, it’s a wired communication accessory, designed to fit inside the canal only one ear at a time, using an FBI and CIA-grade coiled loop earpiece, and a professional-standard microphone and single-button remote unit that gets clipped to your shirt. As is understood by the Secret Service operatives who wear such headsets all the time, it’s…
