Shure SE846-K Sound Isolating Earphones with Quad High Definition MicroDrivers and True Subwoofer Quad Hi-Definition MicroDrivers: For extended high-end clarity and unparalleled low-end performance Patented Earphone Design with Groundbreaking Low-Pass Filter: Provides previously unattainable deep low-end performance of a True Subwoofer without sacrificing clarity or detail Customizable Frequency Response: Adjustable sound signatures available (including balanced, warm or bright) via changeable nozzle inserts and removable, metal nozzle