Increased element rigidity minimizes mechanical distortion & ensures accurate sound reproduction; Voice coils improve signal transmission & conduction for cleaner, clearer sound; Freq resp: 15Hz-20kHz; Closed leatherette earcushions form tight seal to reduce ambient noise & enhance bass; Earcups fold up for protective storage & portability; Heavy-duty, single-entry 8ft straight cord affords ample flexibility of movement; Includes gold-flashed 3.5mm plug & 1/4" adapter; Covered under the KOSS(R) Stereophones Limited Lifetime Warranty;