The ProFlight Series 2 is our most advanced aviation headset yet. Compared to the Bose A20 Aviation Headset, the ProFlight Series 2 has:A new level of comfort achieved through choice of materials, redistribution of weight throughout the headset, and a purposeful in-ear design.Digital active noise reduction with multiple modes of active noise cancellation.A microphone and cable that are side-swappable without tools. Storage in a smaller carrying case.ProFlight Series 2 compared to Bose Aviation Headset Series I and II:Weighs significantly less – 4.5 ounces (128 grams) on head and 9.7 ounces (275 grams) total vs. 18 ounces (510 grams) and is designed for greater comfort, with low clamping force (275 grams of clamping force on average heads).At least 45 hours of battery life from two AA batteries (Series I had a large NICAD system or large plug installation for power; Series II had a six AA battery pack or small dime-size installation).Storage in a more compact space/bag.Less total noise cancellation as compared to the Bose A20.2015 A20 Aviation Headset added features (note that these features are not present in all versions):A2DP: streaming Bluetooth audio.Auto-on (select models using aircraft power).High-performance microphone.Coil cord option.