1" with union bug on the curl. On the reverse two segments of celluloid failed to fold under the collet. One lays against the collet but another piece about .25" long protrudes and can just barely be seen when the piece is viewed from the front. However the piece still displays bright and clean and includes the group's logo with a chain link around a globe encompassing the letters "AR" standing for the name "Arbeter Ring." The group was founded in 1900 by Jewish immigrants from Eastern Europe who sought to promote social values and economic justice. By 1912, around the time of this button, the group had 80,000 members some of which were considered socialists and anarchists. Earliest button we've seen for this group.