This is an authentic United States Navy Mark 12 diving helmet. All Mark 12 helmets were made by the iconic helmet manufacturer Morse Diving Equipment. This example was made in March 1980. Without a doubt, this helmet was part of plenty of underwater action!
 
The helmet, like a majority of surviving Mark 12 helmets, has been decommissioned by the USN. The Navy accomplished this by pushing one side of the neck ring inward, effectively making the helmet unusable. The neck dam ring is present but cracked. The fiberglass shell exhibits obvious signs of heavy use and cracking. 
 
While the Mark V helmet is still the king of USN helmets, the Mark XII was its replacement and is remembered by many during the 1980s. This helmet is a great example for display purposes at an economical price.