Noise isolation far surpassing that of active noise canceling earphonesTransparent, reference-quality sound Frequency response: 20Hz-16kHz, ± 4dBImpedance (ER-4P): 27 Ohms nominalNo batteries required5' cord with 3.5mm stereo phone plugIncludes carrying case, 1/4" stereo adapter plug, six 3-flange eartips, 10 foam eartips, filter changing tool, 4 replacement filters and shirt clip |