brass fastener vs split pin

brass fastener

split pin

noun
  • A stationery fastener that is inserted into punched holes in a stack of paper before being bent to secure them. 

  • A metal fastener with two tines, the ends of which project through an object being fastened and are bent back to hold it in place. 

How often have the words brass fastener and split pin occurred in a corpus of books? (source: Google Ngram Viewer )