The Sennheiser MX W1 delivers the wireless listening freedom and detailed stereo sound. It utilizes "Kleer Technologies" uncompressed digital wireless transmission of high-fidelity sound directly to the "twist to fit" earphones and allows you to enjoy your music for up to 3 hours. This headset feature a frequency response of 19 Hz - 20 kHz and 115 dB sensitivity and weighs 42.53 gr