US Army Attack Helicopter Unit Patches (2001-2021) is a book with 101 pages of photos and illustrations that detail the various unit patches that have been or are currently in use by Attack Helicopter units in the United States Army.This collection was compiled by the author (a US Army aviator) and various contributors over the past 20 years. This volume (the 2nd in a series detailing unit patches used by US Army Aviation) will be extremely useful to the historian and collector.