May 4, 1970 Kent State shooting protest button

vintage 1970 protest button from the may 4, 1970 shootings at kent state university, ohio. discoloration around the edges, see pics. an amazing piece from a tumultuous time during vietnam war. i was given this in 1978 by a friend while we were students there. i’ve never seen another. the 25 stands for the 25 students charged after the shooting for rioting