Presumed circa 1968 based on Eldridge Cleaver's campaign for president of the United States. ~1 3/4" in diameter. Locking pin style back. 

A campaign button for Eldridge Cleaver, one of the key figures in the Black Panther Party. Cleaver ran for president in 1968 as a candidate of the Peace and Freedom Party, one of several put forth by the party that year (due to troubles with various states' laws). GOOD condition. Faint scuffing to the front. Reverse rather rusted.