The Koss QZ900 Noise Cancelling Headphones feature both active and passive noise reduction. The noise cancellation runs on 1 AAA battery which lasts for up to 50hrs before needing to be replaced. In addition to listening to audio, the cord can be removed and the headphones can be used to block out sound as a standalone device. The QZ900s fold flat so you can easily take them with you anywhere and come with a carrying case.
Active noise reduction
Cord unplugs for wire-free passive and active noise cancellation