VERY FINE AND CHOICE. A RARE SOUND FOUR-MARGIN EXAMPLE OF THE 1860 90-CENT IMPERFORATE.
According to Brookman, the 24c, 30c and 90c 1860 Imperforates come from a trial printing of the finished designs submitted to the Postmaster General for final opinion. The designs and colors match the regular issues (unlike essays and trial color proofs). One pair is known of the 90c. For many years these were listed in the front of Scott Catalogue.
A Power Search review did not find another four-margin single offered outside of a set.