Rivet heads carry the following identification marks:
The special "H" as manufacturer's identification symbol
The illustration shows a typical head marking for HR3252-5-04
Material Code Symbols
Aluminum rivets with alloy steel pin = no letter
Aluminum rivets with A-286 CRES pin = symbol "+"
Monel rivets with A-286 CRES pin = letter "M"
Grip range = nominal grip +0/-.063"
Example shown: Head marking = -4 grip (ranges from.250" to .188")