Brown button with orange text.
In 1972 Colorado passed an amendment to their state constitution guaranteeing equal rights for women within the state. In 1976 Colorado's Measure 6 was proposed to remove the equal rights amendment from the state constitution. This button was worn in opposition to the measure, which did not pass.
Sources: Colorado remove language forbidding sex-based inequality, measure 6 (1976). Ballotpedia: The Encyclopedia of American Politics.