armband vs armring

armband

noun
  • A band worn around the arm, usually to symbolize protest or mourning. 

  • An inflatable band worn round the arms to keep afloat in water 

  • A band worn around the arm of the captain of a team. 

armring

noun
  • A ring worn on the arm. 

How often have the words armband and armring occurred in a corpus of books? (source: Google Ngram Viewer )