19th century american victorian era ornamental cast iron interior residential doorknob backplate possibly fabricated by p. & f. corbin or the russell & erwin mfg. company. the c. 1870's passage door backplate contains a circular rosette with protruding collar or thimble (where the doorknob shanks sits). black enameled inlay largely intact. contains a single keyhole opening and two screw holes for mounting purposes. measures approximately 5 1/4 x 1 3/4 inches.