Lot of two San Luis Potosi, Mexico, Banco de San Luis Potosi, 500 pesos front and back proofs, no date (1900-1). Frampton-M489p; SCWPM-S404p. Both uniface. The choice UNC obverse is mounted on a large piece of cardstock with a pencil printer's notation "1900" on back; the AU reverse is mounted on cardstock trimmed to banknote size with some paper rub around the edges and mounting glue on the back. (Estimate: $700 - 1000)