3.5". Unlisted in Hake. Tiny red print mark just left of "Volunteer" in white field, that is trivial and mentioned only for strict accuracy. Otherwise smooth and glossy w/only minor wear in reflected light. NM as made. Examples of this outstanding 1960 campaign button are rarely offered in any condition, let alone in high grade, making this a special opportunity to obtain an impressive 1960 campaign artifact. John Hillhouse Collection.