These octagon glass door knobs are concave in the center. The mercury center is a unique cross design. This set includes two cast brass rosettes. Good condition with appropriate wear from age. Priced as two door knobs, two rosettes, and a spindle. One available. The manufacturer and exact date of creation are unknown. The dimensions are 2.125 in. diameter x 2.375 in. D, rosette 2.125 in. diameter x 0.5 in. D.