One set of inside door braces for the popular triangular Chrome mirror that go on the outside of the door I don't know exactly what year these started being available I believe 79 or 78 through 1991 on the Suburbans and Blazers and the RV series trucks CK trucks up to 87. These bolt inside the door and Brace the mirror from flexing. Also these are good for finding the lower hole to drill as a template.