US Vietnam M-69 Flak vest Body Armor Fragmentation w/ 3/4 collar/
size medium does have damage to the bottom of vest as seen 
 
  classic Vietnam flak vest, the M69 fragmentation vest is one of the most iconic items of the war.
The official name is "Armor body fragmentation with 3/4 collar" but the common name is the M69 flak vest.
(an original medium sized vest weighs 4kg and a replica one weighs 1.4kg) ideal re-enactment.
Features:
Nylon outer.
Two chest pockets with popper closures.
Webbing loops above pockets.
Side adjustments.
Correct pattern chrome zip with flap cover.
Correct cotton labels.
Sizes:
Medium is sized for a 37" to 41" chest.