Petite bronze keyhole back plate with a highly ornate Aesthetic design. Stamped Patented Feb. 9, 1886. BB37. This is in excellent condition. One available. The manufacturer and exact date of creation are unknown. The dimensions are 5.5 in. H x 2.125 in. W x 0.875 in. D, collar 0.5 in. diameter, drop 3.25 in.