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The Type AN-6519 pneumatic life vest was identical to the Army Air Forces' B-4 and the Navy's AN-V-18. The new nomenclature introduced by the AAF on February 1, 1944, separated the three vests by their production date and original procurement. "AN-V-18" by the Navy, "AN-6519" or "AN-6519-1" by either the Navy or AAF, and "Type B-4" by the AAF only. All three vests saw extensive use through WWII.