sennheiser pxc 250 active noise canceling headphones
amazon.com product description portable audio takes on fresh life with quality headphones and sennheiser s folding lightweight closed-ear pxc 250 is designed to keep outside noises out and headphone sound in -- perfect for use in busses and libraries alike . increase the peace the pxc 250 features a noise reduction unit that cancels out background noise . when engaged noisegard active noise reduction drops steady-state low-frequency noise from about 500 hz and below by 15 db -- which the human ear perceives as more than halving the noise -- thus enhancing the clarity of your music . the noise reduction circuit requires 2 aaa batteries not included but the headphones work fine without the circuit engaged . sennheiser s fold and flip design lets you turn the ear pieces 90 degrees and fold the headphones closed . their ported design lets them move more air for greater bass response . what s in the box 6-foot kevlar-reinforced cord .25 - inch stereo adapter airline adapter belt pouch .