Digital Silence DS421D Digital Active Noise Cancelling Ear Buds - Black In ear best in class Wolfson Microelectronics Ambient Noise Cancellation ear buds with 3 manual equalization settings: General (noisy environments), Airplane (removes low frequencies typical for airplanes) and Office (optimizes mid ranges) 14 hours audio playback using Internal rechargeable battery, and automatic convertor when battery expires allows the headphones to be continued to be used without the battery In line best in class Wolfson Microelectronics WM7130 EMS microphone for wind and noise cancellation and quality conversations. 20Hz-22kHz Frequency, 103dB sensitivity, 32 ohm impedance In-line Wolfson WM7130 MEMS active noise cancellation microphone