1.25". Back paper is intact although with scattered moderately dark age marks. The button also has light all over age marks but not particularly dark and button retains its full gloss. Caption along the bottom edge is "1897/Brooklyn B.B. Club." We know of 62 individual players in this series while this button showing the entire team is one of only four done in that style with the others known to us being Buffalo, Pittsburg and Toronto. First we've been able to offer in many decades.