(Note: Measurements are outside max. dimensions unless stated otherwise).18th Century : Robert Adam style backplate for door knob. As per the door furniture at Osterley House.EXTERNAL DIMENSIONS:Width 99mm. (3 15/16")Height 108mm. (4 1/4")Thickness (variable) 4mm. (3/16")INTERNAL DIMENSIONS:Will fit max. diam. Knob backplate of 43mm (1 11/16")