AO-2417-2, 1989, Lou Gehrig, FDC, Add-on Cachet, Cooperstown NY, SC 2417

Add-on cachet is:

A cachet design added to a cover which was originally uncacheted. An add-on cachet should be identified

by maker and date (mine are stamped on the back with the date) so that it is clear that it is not contemporary with the cover.