This is the first button that was issued universally in all Federal penitentiaries after the uniforms were standardized. It was introduced in the summer of 1896, and was issued in either brass/gilt or white metal. Archival evidence seems to suggest that brass examples were used by senior staff of the rank of "Keeper" (or Senior Guard) and above, while white metal ones were used by the junior ranks or "Guards". At some point, this distinction may have been reversed. Research continues. The example pictured is in white metal. The back-mark reads "THOMAS CARLYLE, ASTON, BIRMINGHAM, ENGLAND".