TO GET THE BEST FROM PX, install the latest version of the firmware. This is done via the dedicated Bowers & Wilkins Headphones app, downloadable for free from the AppStore or Google Play Store. SMART POWER - With a 22-hour battery life, PX is always ready; put it down and it goes into power-saving sleep mode; pick it up and you're good to go. PX is the smartest Bluetooth headphone on the market. PX RESPONDS TO YOU - When you need to pause, lift an ear cup. Put PX down and it goes to sleep. Pick it up to resume playing. Worry less about your headphones and enjoy your music more. FEEL MORE OF YOUR MUSIC - Built with the same drive units from our P9 Signature headphones, the PX provides optimized listening performance. We have also subtly angled the drivers to provide a more natural stereo perspective. Impedance: 22 ohms (passive). ADAPTIVE NOISE CANCELLATION - Perfect sound anywhere - on a plane, in the street or in the office. The best adaptive noise cancelling headphones, customizable to your exact preference. Battery life- Up to 22 hours BT/ANC. Up to 29 hours BT/no ANC. Up to 33 hours ANC/wired. Up to 50 hours wired/no ANC. Bowers & Wilkins PERFORMANCE - PX draws on decades of Bowers & Wilkins design experience to take you to the very heart of the music with its breath-taking performance.