Ideal for use with virtually any portable music player, the new K 450 can also connect to your mobile phone or your PC by means of optional adapters and a headset. So you can enjoy your favorite music as you may never have heard it before, as well as make and receive hands-free calls or calls via Skype (with our optional communication kit), all through the same system. And for your convenience we added two lengths of the single sided cable. Of course the foldable K 450 always make a perfect travel companion, wherever you may be. 1/8-1/4 in. (2.5mm/6.3mm) jack adapter Premium carrying case included Color - Navy Frequency response - 11Hz - 29.5kHz Sensitivity - 126dB SPL/V