GB-2000 ANR HeadsetGB-2000 ANR headsets provide up to 21 decibels additional noise reduction. Active noise reduction circuitry senses noise in the earcup, inverts it in phase, and rebroadcasts it through an earphone that acoustically cancels noise.The GB-2000 headset has all the GB-1000 headset features except a cell phone jack. Headsets include ANR modules, an auto-shut-off battery pack, and gel earseals that seal perfectly even if you wear glasses.Expect 6-8 hours of operation on a single 9-volt battery that is easy to change. You can also use a 12 or 24 volt aircraft power adapter.