The mark II on-ear, collapsible mini headphones are equipped with NoiseGard™ technology to cancel up to 80% of droning, fatiguing airplane or bus cabin noise without added bulk or size. They are also equipped with a convenient in-line volume control which enables the listener to adjust playback volume even when the music player is stowed.
The PXC 250-II headphones are foldable and also function as normal headphones without NoiseGard activated. A single AAA battery provides up to 50 hours of NoiseGard performance. An extensive set of accessories - in-flight audio adapter, carrying case and AAA battery- completes the package.
More information: http://en-us.sennheiser.com/travel-headphones-stereo-noise-cancellation-pxc-250-ii