For your consideration, here is an I’m A Syner! Promotional Pinback Button, Pin.  The button has a diameter of 2 1/4 inches.  It has wear on it.  There is a little rust showing through the front of it.  The back has some tarnish on it.  Item pictured is the actual item up for sale and comes from a non-smoking household.  (694.7c9e-.3px1)